docs: add "Set Default Signing" section and refer it

Author: kenjis

contributing/signing.md

@@ -47,7 +47,19 @@ The basic steps are
 - Provide your GPG key passphrase, as prompted, when you do a commit.
 
 Depending on your IDE, you may have to do your Git commits from your Git
-bash shell to use the **-S** option to force the secure signing.
+bash shell to use the `-S` option to force the secure signing.
+
+## Set Default Signing
+
+We recommend you set git securely sign commits without the `-S` option in
+`git commit`.
+
+You can do it by setting `git config --global commit.gpgsign true` and
+`git config --global user.signingkey 3AC5C34371567BD2` to all local repositories.
+Without the `--global` option, the change is applied to one local repository only.
+
+> [!NOTE]
+> `3AC5C34371567BD2` is your GPG Key ID
 
 ## Commit Messages
 

contributing/workflow.md

@@ -179,6 +179,10 @@ For instance, to commit your work from a debugging session:
 
 Just make sure that your commits in a feature branch are all related.
 
+> [!NOTE]
+> We recommend to [Set Default Signing](./signing.md#set-default-signing) for
+> secure signing commits without the `-S` option in `git commit`.
+
 ### GPG-Signing Old Commits
 
 Any developer can forget GPG-signing their commits with the option `-S`, like `git commit -S -m 'Signed GPG'`. In such a case, all you need to do is the following:
@@ -197,10 +201,8 @@ All commits:
 > git push --force-with-lease origin your-branch
 ```
 
-As a faster alternative, you can still securely sign commits without the `-S` option in `git commit` by setting `git config --global commit.gpgsign true` and `git config --global user.signingkey 3AC5C34371567BD2` to all local repositories. Without the `--global` option, the change is applied to one local repository only.
-
-> **Note**
-> `3AC5C34371567BD2` is your GPG Key ID
+As a faster alternative, you can still securely sign commits without the `-S`
+option in `git commit`. See [Set Default Signing](./signing.md#set-default-signing).
 
 ### Changing a Commit Message