commands: support hg help scripting.HGPLAIN

keywords are lowercased within help/minirst...

mercurial/commands.py

@@ -3971,6 +3971,7 b' def help_(ui, name=None, **opts):'
     section = None
     if name and '.' in name:
         name, section = name.split('.', 1)
+        section = section.lower()
 
     text = help.help_(ui, name, **opts)
 

tests/test-help.t

@@ -922,6 +922,10 b' Test repeated config section name'
       "smtp.host"
           Host name of mail server, e.g. "mail.example.com".
   
+Test capitalized section name
+
+  $ hg help scripting.HGPLAIN > /dev/null
+
 Help subsection:
 
   $ hg help config.charsets |grep "Email example:" > /dev/null