Similar to GitHub:
https://github.com/blog/2111-issue-and-pull-request-templates

Priority:
- root
- .gogs
- .github

This commit improves templates readability, since all of them use consistent
indent with all template command blocks indented too.

1. Indents both HTML containers such as <div>, <p> and Go HTML template blocks
   such as {{if}} {{with}}

2. Cleans all trailing white-space

3. Adds trailing last line-break to each file