Move HW Release Process into RTL repo

docs/HWReleaseProcess.md

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+# HW Release process
+
+## Nightly
+
+1. When the **HW Release Workflow** is triggered, the **RTL Submodule Pointer Update** flow is called
+2. The **nightly-verilator** smoke test regression test will be executed against the HEAD of the **main** branch
+    -  If the test passes a **release collateral** archive will be generated and pushed as a Github Artifact
+    -  Repo tag will be added as well in the form "release_v#yyyy#mm#dd_#n"
+
+## RTL Submodule Pointer Update
+
+1. The RTL submodule pointer is compared against the **HEAD of main** of the **caliptra RTL** repo
+    - In case they both point to the same **SHA commit** the rest of the flow is skipped 
+2. A new commit will update the RTL submodule pointer to point to the HEAD of the main branch, and update the registers RDL
+3. A new **nightly release** branch will be created from the HEAD of the **main** branch in the **caliptra-sw** repo
+   - Naming of the branch will indicate it is a nightly release and will have a target point release date (ci_rtl_#yyyy#mm#dd_#n)
+4. The branch will trigger all the CI tests required to submit a PR
+5. Upon succesful completion of the CI tests, the branch will be merged and deleted
+
+## Major Releases
+
+1. The RTL team will consume the **release collateral** generated by the **Nightly Workflow** and verify it in the DV environment. The verification should include RTL synthesis using the chosen tool from the Caliptra WG.
+2. Upon success of the DV verification a new release will be made on the **caliptra** repo
+    -  A ZIP file containing the release collateral will be included as part of the release.
+4. The **caliptra-rtl** and **caliptra-sw** repos will be tagged with a **release** version tag.
+
+## Fail Case
+
+1. Failure in caliptra-sw repo
+    1. Manual intervention required. Create a new issue into the SW Repo. The fix will be made on the **main** branch.
+    2. The next **nightly release** workflow will generate the release
+2. Failure in RTL Repo
+    1. Manual intervention required. Create a new issue into the RTL Repo. Nightly releases are gated to become major until a fix is merged to main.
+    2. While HW fix requires longer time to be submitted, it is acceptable to temporarily diverge from the main branch.
+        - A dev branch will be created from the tip of the RTL main branch, and WA fixes will be applied as individual commits
+        - The RTL Sumbodule pointer in the **caliptra sw** repo will manually be updated to point to the dev branch.
+        - The nightly release workflow will generate all individual patches as part of the collateral archive and list them in the release notes.
+    4. Once the issue is fixed, the RTL dev branch will be deleted and the RTL submodule pointer will be repositioned to the HEAD of the RTL main branch.
+
+## Release Collateral
+
+- Release ZIP File
+  - RTL SRC
+  - ROM binary files (BIN, ELF, and HEX)
+  - Additional Documentation
+  - Caliptra Main Specs
+  - Caliptra ROM Specs
+  - Caliptra RTL Notes
+  - Register Documentation (External)
+  - Header files with:
+    - Register definitions.
+    - Reference code for mailbox, etc.
+  - Release notes TXT file
+  - Which tests were run and which ones passed/failed?
+  - All relevant Git commit hashes from both repos
+- Separate Supporting ZIP File (due to size concerns)
+  - FPGA Bitstream file
+  - C HW model
+    - Headers and static library
+  - Firmware signed (development key) binary files (BIN, ELF)
+  - Integrator Test Checklist
+    - Fuse Matrix
+    - Test List
+    - Development Key
+
+## Release Rules/Opens
+
+- All releases will come from the main branch with nightly cadence.
+- Once a release is made the **nightly release branch** SHALL be deleted.
+
+<br> *Caliptra Release Flow*
+![Caliptra Release Flow Chart](doc/images/Caliptra_release_flow.svg)