Update Git Flow & feature request contributions.

- Directs feature requests and suggestions to the [public roadmap](https://github.com/understrap/understrap-roadmap/issues).
- Introduces `develop` branch and git flow development to protect `main` branch while permitting key contributors to merge PRs into the `develop` branch.

.github/CONTRIBUTING.md

@@ -10,15 +10,17 @@ We love your input! We want to make contributing to this project as easy and tra
 ## We Develop with Github
 We use github to host code, to track issues and feature requests, as well as accept pull requests.
 
-## We Use [Github Flow](https://guides.github.com/introduction/flow/index.html), So All Code Changes Happen Through Pull Requests
-Pull requests are the best way to propose changes to the codebase (we use [Github Flow](https://guides.github.com/introduction/flow/index.html)). We actively welcome your pull requests:
+## We Use [Git Flow](https://www.atlassian.com/git/tutorials/comparing-workflows/gitflow-workflow), So All Code Changes Happen Through Pull Requests
+We actively welcome your pull requests.
 
-1. Fork the repo and create your branch from `master`.
+Pull requests are the best way to propose changes to the codebase. 
+All pull requests should be sumitted to the `develop` branch. 
+This will allow us to grant permissions to key contributors to merge pull requests into the `develop` branch.
+
+1. Fork the repo and create your branch from `develop`.
 2. If you've added code that should be tested, add tests.
 3. If you've changed APIs, update the documentation.
 4. Ensure the test suite passes.
-5. Make sure your code lints.
-6. Issue that pull request!
 
 ## Any contributions you make will be under the GNU GPL version 2
 In short, when you submit code changes, your submissions are understood to be under the same [GNU GPL version 2](https://opensource.org/licenses/GPL-2.0) that covers the project. Feel free to contact the maintainers if that's a concern.

.github/ISSUE_TEMPLATE.md

@@ -2,14 +2,14 @@ Please delete anything that does not apply for you!
 
 ## Issue is about..
   - [ ] a Bug Report
-  - [ ] a Feature Request
-  - [ ] a Suggestion
   - [ ] a Question
   - [ ] I need help
 
+If this issue is a feature request or suggestion, please submit it to our [public roadmap](https://github.com/understrap/understrap-roadmap/issues) instead.
+
 ## Please tell us about your environment:
 
-  - **WordPress Version:** 4.9.x
+  - **WordPress Version:** 5.7.x
   - **OS Version:** [Windows 7 | Windows 8 | Windows 10] | Linux [Distribution / Version] | MacOS [Version] | Android [Version] | iOS [Version]
   - **Browser:** [ all | Chrome XX | Firefox XX | IE XX | Safari XX | Mobile Chrome XX | Android X.X Web Browser | iOS XX Safari ]
   - **Language:** [ all | PHP | SQL | HTML | S/CSS | Javascript | jQuery | ES6 | JSON | XML]

.github/pull_request_template.md

@@ -16,6 +16,9 @@
 ## Checklist:
 <!--- Go over all the following points, and put an `x` in all the boxes that apply. -->
 <!--- If you're unsure about any of these, don't hesitate to ask. We're here to help! -->
+- [ ] I pulled my branch from `develop`.
+- [ ] I am submitting my pull request to `develop`.
+- [ ] I have resolved any conflicts merging this pull request would create.
 - [ ] I have checked that there aren't other open Pull Requests for the same update/change.
 - [ ] My code follows the code style of this project.
 - [ ] I have performed a self-review of my own code.
@@ -28,5 +31,7 @@
 - [ ] `composer lint:php` has passed locally.
 - [ ] I have read the **CONTRIBUTING** document.
 
+## Related Issues or Roadmap requests
+
 ## Further comments
 <!--- If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc... -->