docs: add cosign to developer setup

docs/developer-setup.md

@@ -190,17 +190,29 @@ echo 'eval "$(direnv hook zsh)"' >> ~/.zshrc
 For other shells, follow the instructions at <https://github.com/direnv/direnv/blob/master/docs/hook.md>.
-### Step 2: Install development dependencies
+#### Step 3.5: Setup `cosign`
+
+#### cosign
+
+Cosign a tool used for signature verification for blobs and docker images.
+We use it to verify the authenticity and provenance of the binaries we produce.
+
+```shell
+# Install the latest cosign v2.*.* and make it the global default
+mise install --force cosign 2; mise global cosign 2
+```
+
+### Step 4: Install development dependencies
 Install all the plugins by running:
 ```shell
-./scripts/install-asdf-plugins.sh
+./scripts/prepare-dev-env.sh
 ```
 This will install required `asdf`/`mise` plugins, and install the correct versions of the development tools.
-Note that after pulling changes to the repository, you may sometimes need to re-run `./scripts/install-asdf-plugins.sh` to update your locally installed plugins and tool-versions.
+Note that after pulling changes to the repository, you may sometimes need to re-run `./scripts/prepare-dev-env.sh` to reconfigure your locally development environment.
 ## Updating Tool Versions