Improve our release instructions regarding versioned links

Update our `RELEASE.md` so that we don't forget to bump the download
links in `INSTALL.md` prior to tagging a release. This way, we won't
have a versioned `INSTALL.md` page pointing to an older download link.

Note that this means that the latest version of the `INSTALL.md` page
will point to a broken link, in the short period of time between the
pre-release and the actual release. That's not an issue in our case,
because we don't point to the latest version of our `INSTALL.md` from
our `README.md`. We use versioned links instead, and thus we minimize
the chance that a user may encounter a broken link.

Fixes #1100

RELEASE.md

@@ -17,6 +17,7 @@ Here is a list of tasks that should be done before issuing the release:
 - [ ] Bump the Debian version by adding a new changelog entry in `debian/changelog`
 - [ ] [Bump the minimum Docker Desktop versions](https://github.com/freedomofpress/dangerzone/blob/main/RELEASE.md#bump-the-minimum-docker-desktop-version) in `isolation_provider/container.py`
 - [ ] Bump the dates and versions in the `Dockerfile`
+- [ ] Update the download links in our `INSTALL.md` page to point to the new version (the download links will be populated after the release)
 - [ ] Update screenshot in `README.md`, if necessary
 - [ ] CHANGELOG.md should be updated to include a list of all major changes since the last release
 - [ ] A draft release should be created. Copy the release notes text from the template at [`docs/templates/release-notes`](https://github.com/freedomofpress/dangerzone/tree/main/docs/templates/)
@@ -341,7 +342,7 @@ To publish the release, you can follow these steps:
 
 - [ ] Update the [Dangerzone website](https://github.com/freedomofpress/dangerzone.rocks) to link to the new installers.
 - [ ] Update the brew cask release of Dangerzone with a [PR like this one](https://github.com/Homebrew/homebrew-cask/pull/116319)
-- [ ] Update version and download links in `README.md`
+- [ ] Update version and links to our installation instructions (`INSTALL.md`) in `README.md`
 
 ## Post-release