Add bash-git-prompt in order to have a more descriptive prompt when working with repositories.

Also, update documentation for bash-git-prompt usage

docker-compose.yml

@@ -125,6 +125,7 @@ services:
           - INSTALL_AST=${WORKSPACE_INSTALL_AST}
           - INSTALL_YAML=${WORKSPACE_INSTALL_YAML}
           - INSTALL_MAILPARSE=${WORKSPACE_INSTALL_MAILPARSE}
+          - INSTALL_GIT_PROMPT=${WORKSPACE_INSTALL_GIT_PROMPT}
           - PUID=${WORKSPACE_PUID}
           - PGID=${WORKSPACE_PGID}
           - CHROME_DRIVER_VERSION=${WORKSPACE_CHROME_DRIVER_VERSION}