EPIC: Centralize and update test documentation

Since test doc lives all over the place it is hard to find and navigate, we will do a reorg/rewrite based on feedback received through slack, etc.

Based on comments captured below in this issue, it will be tackled in parts
- Tutorials / Learning-oriented (longer learning session)
- [x] Add new platform support
- reference: https://github.com/adoptium/aqa-tests/wiki/Adding-AQAvit-support-for-a-New-Platform
- [ ] Incorporate vendor tests
- example: See how [smoke tests](https://github.com/adoptium/temurin-build/tree/master/test/functional/buildAndPackage) are incorporated using [vendor test repos](https://github.com/adoptium/ci-jenkins-pipelines/blob/master/pipelines/build/common/openjdk_build_pipeline.groovy#L151-L154) from the build pipeline [code](https://github.com/adoptium/ci-jenkins-pipelines/blob/master/pipelines/build/common/openjdk_build_pipeline.groovy#L295)
- provide another simple example of laying down test material in a repository separate from the main ones that are directly part of "AQAvit", and the minimum requirements for what is currently needed to execute those tests (playlist.xml, build.xml files and testcases)
- [ ] Run tests in a Github action
- [ ] Use TRSS to triage a release
- [ ] ... other tutorials on commonly conducted activities
- How-to Guides / Task-oriented (quick lessons)
- [ ] How to verify a release (with testenv.properties) (see also https://adoptium.net/docs/aqavit-verification/)
- [ ] How to match the right aqa-tests release branch with a particular JDK
- [ ] Rerun a failing test in a Grinder job
- reference: https://github.com/adoptium/aqa-tests/wiki/How-to-Run-a-Grinder-Build-on-Jenkins#rerun-a-failing-openjdk-regression-test to show how to rerun a failing testcase (different from rerunning a failing test target)
- Also show the case for rerunning a failing test target
- [ ] ... other quick how-to's based on lightning talks
- Reference / Information-oriented (detailed encyclopedic knowledge)
- [ ] TKG features reference
- [x] Jenkins features reference - Can start with https://github.com/adoptium/aqa-tests/wiki/How-to-Run-a-Grinder-Build-on-Jenkins#reference
- [ ] TRSS features reference
- [x] Terminology reference (top-level targets down to individual test cases)
- [x] Jenkins label schema (refer to smlambert branch addressing https://github.com/adoptium/infrastructure/issues/93)
- Explanation / Understanding-oriented ('why' things are designed a certain way, 'why' AQAvit exists)
- [x] AQA Definition (Manifesto) - https://github.com/adoptium/aqa-tests/pull/4419
- [x] Scope of AQAvit (AQAvit verification, Cloud compatibility, Developer support)
- [x] Why the '3 layer cake' architecture (via https://github.com/adoptium/aqa-tests/pull/4686)

Noting that this EPIC specifically targets the content that needs to be created, updated and centralized. There will be a separate issue to cover how to display the final set of docs (with some prototyping happening under https://github.com/smlambert/smlambert.github.io and viewable at https://smlambert.github.io/