MesaLink support was added in commit 57348eb97d1b8fc3742e02c but the
backend was never added to the curl_sslbackend enum in curl/curl.h.
This adds the new backend to the enum and updates the relevant docs.
Closes#3195
Reviewed-by: Daniel Stenberg <daniel@haxx.se>
You'll find a mix of various documentation in this directory and
subdirectories, using several different formats. Some of them are not ideal
for reading directly in your browser.
If you'd rather see the rendered version of the documentation, check out the
curl web site's documentation section for
general curl stuff or the libcurl section for
libcurl related documentation.