REPORTING-BUGS: convert to ReST markup

- add a title to the document;
- use :: before verbatim blocks;
- add blank lines where required;
- use protocol for URL references;
- use a verbatim block for the bugs template;
- add cross references to SecurityBugs.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>