doc: add some internal links to man pages

doc/hg.1.txt

@@ -30,7 +30,7 b' COMMAND ELEMENTS'
 
 files...
     indicates one or more filename or relative path filenames; see
-    "FILE NAME PATTERNS" for information on pattern matching
+    `File Name Patterns`_ for information on pattern matching
 
 path
     indicates a path on the local machine
@@ -72,7 +72,7 b' it will be overwritten.'
 
 BUGS
 ----
-Probably lots, please post them to the mailing list (See Resources
+Probably lots, please post them to the mailing list (see Resources_
 below) when you find them.
 
 SEE ALSO

doc/hgrc.5.txt

@@ -40,7 +40,7 b' ones.'
     this file override options in all other configuration files. On
     Unix, most of this file will be ignored if it doesn't belong to a
     trusted user or to a trusted group. See the documentation for the
-    trusted section below for more details.
+    trusted_ section below for more details.
 
 | (Unix) ``$HOME/.hgrc``
 | (Windows) ``%USERPROFILE%\.hgrc``
@@ -309,7 +309,7 b' Settings for extensions that send email '
     email addresses. Cannot be set interactively.
 ``method``
     Optional. Method to use to send email messages. If value is "smtp"
-    (default), use SMTP (see section "[smtp]" for configuration).
+    (default), use SMTP (see the SMTP_ section for configuration).
     Otherwise, use as name of program to run that acts like sendmail
     (takes "-f" option for sender, list of recipients on command line,
     message on stdin). Normally, setting this to "sendmail" or
@@ -774,7 +774,7 b' User interface controls.'
         fail to merge
 
 For more information on configuring merge tools see the
-merge-tools section.
+merge-tools_ section.
 
 ``patch``
     command to use to apply patches. Look for 'gpatch' or 'patch' in