doc: Update release process for snap package

doc/release-process.md

@@ -291,24 +291,48 @@ bitcoin.org (see below for bitcoin.org update instructions).
   - After the pull request is merged, the website will automatically show the newest version within 15 minutes, as well
     as update the OS download links. Ping @saivann/@harding (saivann/harding on Freenode) in case anything goes wrong
 
+- Update other repositories and websites for new version
+
+  - bitcoincore.org blog post
+
+  - bitcoincore.org RPC documentation update
+
+  - Update packaging repo
+
+      - Notify BlueMatt so that he can start building [the PPAs](https://launchpad.net/~bitcoin/+archive/ubuntu/bitcoin)
+
+      - Create a new branch for the major release "0.xx" (used to build the snap package)
+
+      - Notify MarcoFalke so that he can start building the snap package
+
+        - https://code.launchpad.net/~bitcoin-core/bitcoin-core-snap/+git/packaging (Click "Import Now" to fetch the branch)
+        - https://code.launchpad.net/~bitcoin-core/bitcoin-core-snap/+git/packaging/+ref/0.xx (Click "Create snap package")
+        - Name it "bitcoin-core-snap-0.xx"
+        - Leave owner and series as-is
+        - Select architectures that are compiled via gitian
+        - Leave "automatically build when branch changes" unticked
+        - Tick "automatically upload to store"
+        - Put "bitcoin-core" in the registered store package name field
+        - Tick the "edge" box
+        - Put "0.xx" in the track field
+        - Click "create snap package"
+        - Click "Request builds" for every new release on this branch (after updating the snapcraft.yml in the branch to reflect the latest gitian results)
+        - Promote release on https://snapcraft.io/bitcoin-core/releases if it passes sanity checks
+
+  - This repo
+
+      - 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.
+
 - Announce the release:
 
   - bitcoin-dev and bitcoin-core-dev mailing list
 
   - Bitcoin Core announcements list https://bitcoincore.org/en/list/announcements/join/
 
-  - bitcoincore.org blog post
-
-  - bitcoincore.org RPC documentation update
-
   - Update title of #bitcoin on Freenode IRC
 
   - Optionally twitter, reddit /r/Bitcoin, ... but this will usually sort out itself
 
-  - Notify BlueMatt so that he can start building [the PPAs](https://launchpad.net/~bitcoin/+archive/ubuntu/bitcoin)
-
-  - 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.
-
   - Celebrate