[Docs] Release process updates

Updates to `doc/release-process.md`:

- Create a pinned meta-issue dedicated to testing the release candidate and communicate it in release announcements where useful. The former is done in practice (e.g. bitcoin#15555, bitcoin#14902) and the latter addresses the discussion here: https://x0f.org/web/statuses/101753569204220416.

- Create a Release Notes draft wiki for collaborative editing at https://github.com/bitcoin-core/bitcoin-devwiki/wiki as seen for v0.17.0 and the current v0.18.0 release.

- As per http://www.erisian.com.au/bitcoin-core-dev/log-2019-03-28.html#l-342, for the period during which the notes are being edited on the wiki, the version on the branch should be wiped and replaced with a link to the wiki which should be used for all announcements until final.

- Before final, remove the "Needs release note" label from relevant PRs/issues and merge the release notes from the wiki into the branch.

- Steal/adapt/merge the updates in bitcoin#15692.

doc/release-notes.md

@@ -1,5 +1,19 @@
-(note: this is a temporary file, to be added-to by anybody, and moved to
-release-notes at release time)
+*After branching off for a major version release of Bitcoin Core, use this
+template to create the initial release notes draft.*
+
+*The release notes draft is a temporary file that can be added-to by anyone. See
+[/doc/developer-notes.md#release-notes](/doc/developer-notes.md#release-notes)
+for the process.*
+
+*Create the draft, named* **\*version\*-Release-Notes-Draft,** *as a
+collaborative wiki in:*
+
+https://github.com/bitcoin-core/bitcoin-devwiki/wiki/
+
+*Before the final release, move the notes back to this git repository.*
+
+\*version\* Release Notes Draft
+=============================
 
 Bitcoin Core version *version* is now available from:
 

doc/release-process.md

@@ -26,7 +26,10 @@ Before every major release:
 * Update [`src/chainparams.cpp`](/src/chainparams.cpp) m_assumed_blockchain_size and m_assumed_chain_state_size with the current size plus some overhead.
 * Update `src/chainparams.cpp` chainTxData with statistics about the transaction count and rate. Use the output of the RPC `getchaintxstats`, see
   [this pull request](https://github.com/bitcoin/bitcoin/pull/12270) for an example. Reviewers can verify the results by running `getchaintxstats <window_block_count> <window_last_block_hash>` with the `window_block_count` and `window_last_block_hash` from your output.
-* Update version of `contrib/gitian-descriptors/*.yml`: usually one'd want to do this on master after branching off the release - but be sure to at least do it before a new major release
+* Before branching off the release, clear the release notes and move them to the wiki (see "Write the release notes" below).
+* After branching off the release:
+    - Update the link to the release notes draft in `doc/release-notes.md`
+    - Update the version of `contrib/gitian-descriptors/*.yml` on master
 
 ### First time / New builders
 
@@ -40,23 +43,33 @@ Check out the source code in the following directory hierarchy.
     git clone https://github.com/devrandom/gitian-builder.git
     git clone https://github.com/bitcoin/bitcoin.git
 
-### Bitcoin maintainers/release engineers, suggestion for writing release notes
+### Write the release notes
 
-Write release notes. git shortlog helps a lot, for example:
+Open a draft of the release notes for collaborative editing at https://github.com/bitcoin-core/bitcoin-devwiki/wiki.
+
+For the period during which the notes are being edited on the wiki, the version on the branch should be wiped and replaced with a link to the wiki which should be used for all announcements until `-final`.
+
+Write the release notes. `git shortlog` helps a lot, for example:
 
     git shortlog --no-merges v(current version, e.g. 0.7.2)..v(new version, e.g. 0.8.0)
 
 (or ping @wumpus on IRC, he has specific tooling to generate the list of merged pulls
-and sort them into categories based on labels)
+and sort them into categories based on labels).
 
-Generate list of authors:
+Generate the list of authors:
 
     git log --format='- %aN' v(current version, e.g. 0.16.0)..v(new version, e.g. 0.16.1) | sort -fiu
 
-Tag version (or release candidate) in git
+Tag the version (or release candidate) in git:
 
     git tag -s v(new version, e.g. 0.8.0)
 
+Before the final release:
+
+  - Merge the release notes from the wiki into the branch
+
+  - Ensure the "Needs release note" label is removed from all relevant pull requests and issues
+
 ### Setup and perform Gitian builds
 
 If you're using the automated script (found in [contrib/gitian-build.py](/contrib/gitian-build.py)), then at this point you should run it with the "--build" command. Otherwise ignore this.
@@ -323,7 +336,9 @@ bitcoin.org (see below for bitcoin.org update instructions).
 
       - Archive release notes for the new version to `doc/release-notes/` (branch `master` and branch of the release)
 
-      - Create a [new GitHub release](https://github.com/bitcoin/bitcoin/releases/new) with a link to the archived release notes.
+      - Create a [new GitHub release](https://github.com/bitcoin/bitcoin/releases/new) with a link to the archived release notes
+
+      - Create a pinned meta-issue for testing the release (see [here](https://github.com/bitcoin/bitcoin/issues/15555) for an example) and provide a link to it in the release announcements where useful
 
 - Announce the release: