XEP-0158: Fix some typos

Signed-off-by: Maxime “pep” Buquet <pep@bouah.net>

xep-0158.xml

@@ -109,7 +109,7 @@
 </header>
 
 <section1 topic='Introduction' anchor='intro'>
-  <p>The appearance of large public IM services based on &xmppcore; and &xmppim; makes it desirable to implement protocols that <em>discourage</em> the sending of large quantities of instant messaging spam (a.k.a. "spim") or, in general, abusive traffic. Abusive stanzas could be generated by XMPP clients connected to legitimate servers or by XMPP servers with virtual clients, where the malicious entities are hosted on networks of "zombie" machines. Such abusive stanas could take many forms; a full taxonomy is outside the scope of this document.</p>
+  <p>The appearance of large public IM services based on &xmppcore; and &xmppim; makes it desirable to implement protocols that <em>discourage</em> the sending of large quantities of instant messaging spam (a.k.a. "spim") or, in general, abusive traffic. Abusive stanzas could be generated by XMPP clients connected to legitimate servers or by XMPP servers with virtual clients, where the malicious entities are hosted on networks of "zombie" machines. Such abusive stanzas could take many forms; a full taxonomy is outside the scope of this document.</p>
   <p>One technique developed to combat abusive messages and behavior via non-XMPP technologies requires humans to be differentiated from bots using a "Completely Automated Public Turing Test to Tell Computers and Humans Apart" or CAPTCHA (see &lt;<link url='http://www.captcha.net/'>http://www.captcha.net/</link>&gt;). These challenge techniques are easily adapted to discourage XMPP abuse. The very occasional inconvenience of responding to a CAPTCHA (e.g., when creating an IM account or sending a message to a new correspondent) is small and perfectly acceptable -- especially when compared to the countless robot-generated interruptions people might otherwise have to filter every day.</p>
   <p>An alternative technique to CAPTCHAs requires Desktop PC clients to undertake a <span class='ref'>Hashcash</span> <note>Hashcash &lt;<link url='http://hashcash.org/'>http://hashcash.org/</link>&gt;.</note> challenge. These are completely transparent to PC users. They require clients to perform specified CPU-intensive work, making it difficult to send large amounts of abusive traffic.</p>
   <p>Both CAPTCHAs and hashcash have been criticized regarding their effectiveness (or lack thereof). Therefore, the challenge protocol specified herein provides a great deal of flexibility, so that challenges can include CAPTCHAs, hashcash, word puzzles, so-called kitten authentication, and any other mechanism that may be developed in the future.</p>
@@ -143,7 +143,7 @@
     </section3>
     <section3 topic='Challenge Stanza' anchor='protocol-challenge'>
      <p>Upon receiving a triggering stanza, an entity MAY send a "challenge stanza". An entity MUST NOT send a challenge stanza under any other circumstances. The entity that generates the challenge stanza is called the "challenger".</p>
-    <p>The challange stanza consists of an XMPP &MESSAGE; stanza containing a data form for the sender to fill out, formatted according to &xep0004;, optionally along with a &BODY; and other elements. The following rules apply to the challenge stanza.</p>
+    <p>The challenge stanza consists of an XMPP &MESSAGE; stanza containing a data form for the sender to fill out, formatted according to &xep0004;, optionally along with a &BODY; and other elements. The following rules apply to the challenge stanza.</p>
     <ol>
       <li>The challenge stanza MUST include an 'id' attribute set to the challenge ID (i.e., a unique identifier for this challenge within the challenger's application).</li>
       <li>The challenge stanza SHOULD include a &BODY; element that provides an explanation of the challenge for clients that do not yet support CAPTCHA forms.</li>