[glade] Update Markdown formatting in CONTRIBUTING.md

[Juan Pablo Ugarte <jpu src gnome org>]

commit 4560bd511af87b8eee192febeb18340e63ade930
Author: Jonathan Paugh <jpaugh gmx us>
Date:   Sun Apr 11 14:35:29 2021 +0000

    Update Markdown formatting in CONTRIBUTING.md

 CONTRIBUTING.md | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)
---
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 1f716f57..a97cc24f 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -2,7 +2,7 @@ Glade official git repository is hosted by the GNOME foundation at
 gitlab.gnome.org
 
 Mailing List
-~~~~~~~~~~~~
+============
 Glade discussion takes place on glade-devel-list gnome org
 
 To subscribe or to consult archives visit
@@ -10,47 +10,55 @@ To subscribe or to consult archives visit
 
 
 GitLab
-~~~~~~~~
+========
 Glade bugs are tracked at
 
        https://gitlab.gnome.org/GNOME/glade
 
 
 GIT
-~~~
+===
 You can browse the source code at https://gitlab.gnome.org/GNOME/glade
 To check out a copy of Glade you can use the following command:
 
        git clone https://gitlab.gnome.org/GNOME/glade.git
 
 Patches
-~~~~~~~
+=======
 Patches must be in the unified format (diff -u) and must include a
 ChangeLog entry. Please send all patches to bugzilla.
 
 It is better to use git format-patch command
 
+```
 git format-patch HEAD^
+```
 
 Coding Style
-~~~~~~~~~~~~
+============
 Code in Glade should follow the GNU style of GNOME Programming Guidelines
 (https://developer.gnome.org/programming-guidelines/stable/c-coding-style.html.en),
 basically this means being consistent with the surrounding code.
 The only exception is that we prefer having braces always on a new line
 e.g.:
 
+```
 if (...)
   {
     ...
   }
+```
+
 
 Note however that a lot of the current codebase still uses the following
 style:
 
+```
 if (...) {
   ...
 }
+```
+
 
 Over time we'll migrate to the preferred form.
 
@@ -58,11 +66,11 @@ Naming conventions:
 - function names should be lowercase and prefixed with the
   file name (or, if the function is static and the name too long,
   with an abbreviation), e.g:
-  glade_project_window_my_function ()
-  gpw_my_loooooooooong_named_fuction ()
+  `glade_project_window_my_function ()`
+  `gpw_my_loooooooooong_named_fuction ()`
 - variable names should be lowercase and be short but self explanatory;
   if you need more than one word use an underscore, e.g:
-  my_variable
+  `my_variable`
 
 Also try to order your functions so that prototypes are not needed.