Refactor export GPG_TTY command to add line break

The command to add `GPG_TTY` does not update the shell config correctly if the file ends in a comment.

I previously installed pnpm so running the command changed my  `.zshrc` file to:
```
#pnpm endexport GPG_TTY=$(tty)
```

Fixed by updating each instance of the command to:
```
echo -e '\nexport GPG_TTY=\$(tty)'
```

Author: AlmostEfficient

content/authentication/managing-commit-signature-verification/telling-git-about-your-signing-key.md

@@ -39,13 +39,13 @@ If you have multiple GPG keys, you need to tell Git which one to use.
 {% data reusables.gpg.set-auto-sign %}
 1. If you aren't using the GPG suite, run the following command in the `zsh` shell to add the GPG key to your `.zshrc` file, if it exists, or your `.zprofile` file:
   ```shell
-  $ if [ -r ~/.zshrc ]; then echo 'export GPG_TTY=$(tty)' >> ~/.zshrc; \
-    else echo 'export GPG_TTY=$(tty)' >> ~/.zprofile; fi
+  $ if [ -r ~/.zshrc ]; then echo -e '\nexport GPG_TTY=\$(tty)' >> ~/.zshrc; \
+    else echo -e '\nexport GPG_TTY=\$(tty)' >> ~/.zprofile; fi
   ```
   Alternatively, if you use the `bash` shell, run this command:
   ```shell
-  $ if [ -r ~/.bash_profile ]; then echo 'export GPG_TTY=$(tty)' >> ~/.bash_profile; \
-    else echo 'export GPG_TTY=$(tty)' >> ~/.profile; fi
+  $ if [ -r ~/.bash_profile ]; then echo -e '\nexport GPG_TTY=\$(tty)' >> ~/.bash_profile; \
+    else echo -e '\nexport GPG_TTY=\$(tty)' >> ~/.profile; fi
   ```
 1. Optionally, to prompt you to enter a PIN or passphrase when required, install `pinentry-mac`. For example, using [Homebrew](https://brew.sh/):
   ```shell
@@ -97,7 +97,7 @@ If you have multiple GPG keys, you need to tell Git which one to use.
 {% data reusables.gpg.set-auto-sign %}
 1. To add your GPG key to your `.bashrc` startup file, run the following command:
   ```bash
-  $ [ -f ~/.bashrc ] && echo 'export GPG_TTY=$(tty)' >> ~/.bashrc
+  $ [ -f ~/.bashrc ] && echo -e '\nexport GPG_TTY=\$(tty)' >> ~/.bashrc
   ```
 {% endlinux %}
 {% ifversion ssh-commit-verification %}