libcurl.3: fix formatting

refer to functions with the man page section properly

docs/libcurl/libcurl.3

@@ -148,18 +148,16 @@ the library code.  For example, when libcurl is built for SSL
 capability via the GNU TLS library, there is an elaborate tree inside
 that library that describes the SSL protocol.
 
-\fIcurl_global_init()\fP is the function that you must call.  This may
+\fIcurl_global_init(3)\fP is the function that you must call.  This may
-allocate resources (e.g. the memory for the GNU TLS tree mentioned
+allocate resources (e.g. the memory for the GNU TLS tree mentioned above), so
-above), so the companion function \fIcurl_global_cleanup()\fP releases
+the companion function \fIcurl_global_cleanup(3)\fP releases them.
-them.
 
-The basic rule for constructing a program that uses libcurl is this:
+The basic rule for constructing a program that uses libcurl is this: Call
-Call \fIcurl_global_init()\fP, with a \fICURL_GLOBAL_ALL\fP argument,
+\fIcurl_global_init(3)\fP, with a \fICURL_GLOBAL_ALL\fP argument, immediately
-immediately after the program starts, while it is still only one
+after the program starts, while it is still only one thread and before it uses
-thread and before it uses libcurl at all.  Call
+libcurl at all.  Call \fIcurl_global_cleanup(3)\fP immediately before the
-\fIcurl_global_cleanup()\fP immediately before the program exits, when
+program exits, when the program is again only one thread and after its last
-the program is again only one thread and after its last use of
+use of libcurl.
-libcurl.
 
 You can call both of these multiple times, as long as all calls meet
 these requirements and the number of calls to each is the same.
@@ -184,48 +182,42 @@ your code doesn't know about other parts of the program -- it doesn't
 know whether they use libcurl or not.  And its code doesn't necessarily
 run at the start and end of the whole program.
 
-A module like this must have global constant functions of its own,
+A module like this must have global constant functions of its own, just like
-just like \fIcurl_global_init()\fP and \fIcurl_global_cleanup()\fP.
+\fIcurl_global_init(3)\fP and \fIcurl_global_cleanup(3)\fP.  The module thus
-The module thus has control at the beginning and end of the program
+has control at the beginning and end of the program and has a place to call
-and has a place to call the libcurl functions.  Note that if multiple
+the libcurl functions.  Note that if multiple modules in the program use
-modules in the program use libcurl, they all will separately call the
+libcurl, they all will separately call the libcurl functions, and that's OK
-libcurl functions, and that's OK because only the first
+because only the first \fIcurl_global_init(3)\fP and the last
-\fIcurl_global_init()\fP and the last \fIcurl_global_cleanup()\fP in a
+\fIcurl_global_cleanup(3)\fP in a program change anything.  (libcurl uses a
-program change anything.  (libcurl uses a reference count in static
+reference count in static memory).
-memory).
 
-In a C++ module, it is common to deal with the global constant
+In a C++ module, it is common to deal with the global constant situation by
-situation by defining a special class that represents the global
+defining a special class that represents the global constant environment of
-constant environment of the module.  A program always has exactly one
+the module.  A program always has exactly one object of the class, in static
-object of the class, in static storage.  That way, the program
+storage.  That way, the program automatically calls the constructor of the
-automatically calls the constructor of the object as the program
+object as the program starts up and the destructor as it terminates.  As the
-starts up and the destructor as it terminates.  As the author of this
+author of this libcurl-using module, you can make the constructor call
-libcurl-using module, you can make the constructor call
+\fIcurl_global_init(3)\fP and the destructor call \fIcurl_global_cleanup(3)\fP
-\fIcurl_global_init()\fP and the destructor call
+and satisfy libcurl's requirements without your user having to think about it.
-\fIcurl_global_cleanup()\fP and satisfy libcurl's requirements without
-your user having to think about it.
 
-\fIcurl_global_init()\fP has an argument that tells what particular
+\fIcurl_global_init(3)\fP has an argument that tells what particular parts of
-parts of the global constant environment to set up.  In order to
+the global constant environment to set up.  In order to successfully use any
-successfully use any value except \fICURL_GLOBAL_ALL\fP (which says to
+value except \fICURL_GLOBAL_ALL\fP (which says to set up the whole thing), you
-set up the whole thing), you must have specific knowledge of internal
+must have specific knowledge of internal workings of libcurl and all other
-workings of libcurl and all other parts of the program of which it is
+parts of the program of which it is part.
-part.
 
-A special part of the global constant environment is the identity of
+A special part of the global constant environment is the identity of the
-the memory allocator.  \fIcurl_global_init()\fP selects the system
+memory allocator.  \fIcurl_global_init(3)\fP selects the system default memory
-default memory allocator, but you can use \fIcurl_global_init_mem()\fP
+allocator, but you can use \fIcurl_global_init_mem(3)\fP to supply one of your
-to supply one of your own.  However, there is no way to use
+own.  However, there is no way to use \fIcurl_global_init_mem(3)\fP in a
-\fIcurl_global_init_mem()\fP in a modular program -- all modules in
+modular program -- all modules in the program that might use libcurl would
-the program that might use libcurl would have to agree on one
+have to agree on one allocator.
-allocator.
 
-There is a failsafe in libcurl that makes it usable in simple
+There is a failsafe in libcurl that makes it usable in simple situations
-situations without you having to worry about the global constant
+without you having to worry about the global constant environment at all:
-environment at all: \fIcurl_easy_init()\fP sets up the environment
+\fIcurl_easy_init(3)\fP sets up the environment itself if it hasn't been done
-itself if it hasn't been done yet.  The resources it acquires to do so
+yet.  The resources it acquires to do so get released by the operating system
-get released by the operating system automatically when the program
+automatically when the program exits.
-exits.
 
 This failsafe feature exists mainly for backward compatibility because
 there was a time when the global functions didn't exist.  Because it