docs: encrypt CLI usage (#21162)

Co-authored-by: HonkingGoose <34918129+HonkingGoose@users.noreply.github.com>

docs/usage/configuration-options.md

@@ -802,16 +802,41 @@ For the full list of available managers, see the [Supported Managers](https://do
 
 ## encrypted
 
-Use this to encrypt secrets in a way which can be stored in repository configs.
+Before you put any secrets in your repository configuration, encrypt the secrets.
+You can encrypt secrets using either a HTML page, or the CLI.
 
-See [Private module support](https://docs.renovatebot.com/getting-started/private-packages) for details on how this is used to encrypt npm tokens.
+To encrypt secrets for the hosted Mend Renovate app for github.com with a HTML page, go to [app.renovatebot.com/encrypt](https://app.renovatebot.com/encrypt) and complete the form.
+If you're self-hosting Renovate, you may download and edit the form, to use your own PGP public key.
+
+You can also encrypt secrets from the CLI, using the `curl`, `echo`, `jq`, `gpg`, `grep` and `tr` CLI programs.
+Here is an example:
+
+```
+curl https://app.renovatebot.com/renovate.pgp --output renovate.pgp
+echo -n '{"o":"your-organization", "r":"your-repository (optional)", "v":"your-secret-value"}' | jq . -c | gpg --encrypt -a --recipient-file renovate.pgp | grep -v '^----' | tr -d '\n'
+```
+
+The above script uses:
+
+- `curl` to download the Mend Renovate hosted app's public key
+- `echo` to echo a JSON object into `jq`
+- `jq` to validate the JSON and then compact it
+- `gpg` to encrypt the contents
+- `grep` and `tr` to extract the encrypted payload which we will use
+
+The `jq` step is optional, you can leave it out if you wish.
+Its primary value is validating that the string you echo to `gpg` is valid JSON, and compact.
 
 <!-- prettier-ignore -->
 !!! note
     Encrypted secrets must have at least an org/group scope, and optionally a repository scope.
     This means that Renovate will check if a secret's scope matches the current repository before applying it, and warn/discard if there is a mismatch.
 
-Encrypted secrets typically have a single org, but you may encrypt a secret with more than one, e.g. specifying `org1,org2` to allow the secret to be used in both `org1` and `org2` organizations.
+Encrypted secrets usually have a single organization.
+But you may encrypt a secret with more than one organization, for example: `org1,org2`.
+This way the secret can be used in both the `org1` and `org2` organizations.
+
+For more information on how to use secrets for private packages, read [Private package support](https://docs.renovatebot.com/getting-started/private-packages).
 
 ## excludeCommitPaths