[Improve Existing Best Practice Guide]: Update CONTRIBUTING guide template with internal team contribution model

[riverma]

Checked for duplicates

Yes - I've already checked

Best Practice Guide

Governance

Best Practice Guide Sections

Starter Kits

Describe the improvement

Our CONTRIBUTING.md guide currently is targeted to describing and encouraging contributions from external team members - i.e. the fork-the-repository and create a PR against the main branch. Comments and feedback from @anilnatha suggest that we should include guidance on branching structure following "GitFlow" best practices for internal team members to collaborate better. The following specifics were discussed and recommended by @anilnatha:

• Recommendations on how internal team members should govern branches and overall merger / releases of software as a team
• Recommendation on GitHub teams that should exist to support contributing model - aka the SLIM Governance Model

Additionally, some extraneous ideas were discussed that should be the subject of a future, separate ticket:

• Automation to include default branches within a SLIM repository template
• Automation to include Github.com configuration settings recommended to ensure proper collaboration among team members
• Automation to enact / create necessary GitHub teams and permissions