docs: update release process for deterministic publish workflow (#166)

## Summary

Updates `docs/release-process.md` to reflect the new deterministic
release workflow for MetaMask Extension
([INFRA-3250](https://consensyssoftware.atlassian.net/browse/INFRA-3250),
[RAPID](https://consensyssoftware.atlassian.net/wiki/spaces/PRDC/pages/400673538083/RAPID+Metamask+Extension+Deterministic+Release+Workflow)).

**What changed in the workflow:**
- The old `tag-release-branch` GitHub Action (which only added a tag) is
replaced by the new `publish-release-from-release-head` workflow
(manually triggered)
- Production build, tag, and GitHub release are now created from the
release branch HEAD **before** merging to `stable`, enforcing `Tag SHA
== Build SHA == Release target SHA`
- Merging to `stable` is now a sync step only — it no longer triggers an
automatic production build

**Diagram nodes updated:**
- `CURRENT10`: `'Tag Release Branch' GitHub Action` →
`'publish-release-from-release-head' workflow`
- `CURRENT11`: `Release tag is added on the release branch` →
`Production build, tag, and GitHub release are created from release
branch HEAD`
- `STABLE1`: `A new production build is automatically created and posted
on the repo's releases page` → `Release branch is merged into 'stable'
branch`

## References

- Jira:
[INFRA-3250](https://consensyssoftware.atlassian.net/browse/INFRA-3250)
- RAPID: [Metamask Extension Deterministic Release
Workflow](https://consensyssoftware.atlassian.net/wiki/spaces/PRDC/pages/400673538083/RAPID+Metamask+Extension+Deterministic+Release+Workflow)
- Implementation PR: MetaMask/metamask-extension#39285

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Qbandev

docs/release-process.md

@@ -54,14 +54,14 @@ subgraph Current [Current release branch: 'release/x.y.z']
     CURRENT6 --> CURRENT8[Release is approved by all teams]
     CURRENT7 --> CURRENT8
     CURRENT8 --> CURRENT9[Release is approved by Release Engineer, Release QA, and Release Manager]
-    CURRENT9 --> CURRENT10['Tag Release Branch' GitHub Action is triggered by Release Engineer]
-    CURRENT10 --> CURRENT11[Release tag is added on the release branch]
+    CURRENT9 --> CURRENT10[Release Engineer manually triggers 'publish-release-from-release-head' workflow on the release branch]
+    CURRENT10 --> CURRENT11[Production build, tag, and GitHub release are created from release branch HEAD]
     CURRENT11 --> CURRENT12[Release engineer merges x.y.z release PR into 'stable' branch]
 end
 
 subgraph Stable [Stable branch: 'stable']
     style Stable fill:#26084d,stroke:#000,stroke-width:2px,color:#fff
-    CURRENT12 -->|merge PR| STABLE1[A new production build is automatically created and posted on the repo's releases page]
+    CURRENT12 -->|merge PR| STABLE1[Release branch is merged into 'stable' branch]
     STABLE1 --> STABLE2[Release Engineer submits x.y.z production build to the store]
 end