lfs: dedent documentation section about .hglfs file

The leading ".hglfs::" is interpreted as a macro in generated man page
and, as it is unknown, the whole section does not render. Also, having
the section marked as preformatted (::) makes it render verbatim in
HTML, which is not desired as the text contains formatting markers. So
we just dedent the section and remove the ".hglfs::" line. The example
file is still indented and rendered preformatted.

hgext/lfs/__init__.py

@@ -53,8 +53,6 b' locally. Both committing and downloadin'
 file to a usercache, to speed up future access.  See the `usercache`
 config setting described below.
 
-.hglfs::
-
     The extension reads its configuration from a versioned ``.hglfs``
     configuration file found in the root of the working directory. The
     ``.hglfs`` file uses the same syntax as all other Mercurial