Add issue templates(Proposal and Documentation)

[Akash20x]

Issue that this pull request solves

Closes: #394

Proposed changes

Add documentation and proposal issue templates

Types of changes

Put an x in the boxes that apply

• [ ] Bugfix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] Documentation update (Documentation content changed)
• [ ] Other (please describe):

Checklist

Put an x in the boxes that apply

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings

Screenshots

Please attach the screenshots of the changes made in case of change in user interface

Other information

Any other information that is important to this pull request

[rpotter12]

@Akash20x Maybe I will handle this Template thing. I have already added new template which is given by github only. So there is no need of these. :)

[Akash20x]

OK