Add support for parsing links in .rst files

[raukadah]

It would be nice to have the support for parsing links in .rst (restructured) text files.

[amolkahat]

@raukadah why we need rst file parser? If issue #1 got fixed then we don't need to write rst parser.

[raukadah]

In the current implementation, It parses markdown files and extract links for that, we need the same process for .rst files. Yes if #1 got fixed, It will remove the dependency.