add command how to verify git credentials

docs/source/dev_docs/setup/part_2_git_ssh.rst

@@ -1,14 +1,22 @@
 Setup part 2: Git and SSH
 -------------------------------------------
 
-Before installing and using CoLRev, please update your git credentials (using the shell / ``Ctrl``\ +\ ``Alt``\ +\ ``T``):
+Before installing and using CoLRev, please install git and set up credentials (using the shell / ``Ctrl``\ +\ ``Alt``\ +\ ``T``):
 
 ::
 
-   sudo apt install git
+   sudo apt update && sudo apt install git
    git config --global user.name "Lisa Smith"
    git config --global user.email "lisa.smith@stud.uni-bamberg.de"
    git config --global credential.helper store
 
+Verify that the credential were correctly set up:
+
+::
+
+   cat ~/.gitconfig
+
+If credentials were set up incorrectly, please rerun the commands above.
+
 Create a SSH key pair and register the public key at Github
 (`steps <https://docs.github.com/en/authentication/connecting-to-github-with-ssh/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent>`__).