Merge bitcoin/bitcoin#35132: doc: update release process to mention security advisories pre-announcements

4abc0c2e04 doc: update release process to mention security advisories pre-announcements (Antoine Poinsot)

Pull request description:

  We missed a pre-announcement with the release of 31.0. This updates the release process docs to make sure we check those before publishing a major release.

ACKs for top commit:
  achow101:
    ACK 4abc0c2e04
  jonatack:
    ACK 4abc0c2e04

Tree-SHA512: 63d1def3d4144de7992b539d41a496c98bc81b33e2a9c27af55933a696050123a0c967253093728f0553f13aca12acec8a51efbeda0936077646c379c37219d6

doc/release-notes-empty-template.md

@@ -20,6 +20,15 @@ To receive security and update notifications, please subscribe to:
 
   <https://bitcoincore.org/en/list/announcements/join/>
 
+With the release of this new major version, versions *version minus 3* and
+older are at "End of Life" and will no longer receive updates.
+
+In accordance with the security policy, we will in two weeks disclose:
+
+* Medium and high severity vulnerabilities fixed in *version minus 2*. There are N of these.
+
+* Low severity vulnerabilities fixed in *version*. There are M of these.
+
 How to Upgrade
 ==============
 

doc/release-process.md

@@ -25,6 +25,7 @@ Release Process
   - set `CLIENT_VERSION_MINOR` to `0`
   - set `CLIENT_VERSION_BUILD` to `0`
   - set `CLIENT_VERSION_IS_RELEASE` to `true`
+* Check with the security team whether there is any security advisory to pre-announce.
 
 #### Before branch-off
 
@@ -296,7 +297,7 @@ cat "$VERSION"/*/all.SHA256SUMS.asc > SHA256SUMS.asc
 
   - Create a [new GitHub release](https://github.com/bitcoin/bitcoin/releases/new) with a link to the archived release notes
 
-- Announce the release:
+- Announce the release, along with any security advisory pre-announcements:
 
   - bitcoin-dev and bitcoin-core-dev mailing list