Enhance GitHub template

[Lee-W]

Types of changes

Please put an x in the box that applies

• Bugfix
• New feature
• Refactoring
• Breaking change (any change that would cause existing functionality to not work as expected)
• Documentation Update
• Other (please describe): GitHub template

Description

• Initial GitHub template for issues
• Add detailed content to pull request template

Checklist:

• Add test cases to all the changes you introduce
• Run ./script/lint and ./script/test locally to ensure this change passes linter check and test
• Test the changes on the local machine manually
• Update the documentation for the changes

Steps to Test This Pull Request

• Create a pull request/issue

Expected behavior

• Feature Request / Bug Report / Document should appear as options when creating an issue
• The template used in this pull request show be seen when creating a new pull request

Related Issue

Additional context

[codecov]

Codecov Report

Merging #189 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #189   +/-   ##
=======================================
  Coverage   92.14%   92.14%           
=======================================
  Files          35       35           
  Lines         967      967           
=======================================
  Hits          891      891           
  Misses         76       76           

Flag	Coverage Δ
#unittests	92.14% <100.00%> (ø)

Impacted Files	Coverage Δ
commitizen/__version__.py	100.00% <100.00%> (ø)

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[woile]

LGTM, thanks