add timeout to git operations

doc/profile.conf.example

@@ -201,6 +201,10 @@ TERM=xterm-256color
 # Include Git dirty marker and upstream drift (+ahead/-behind) in the context.
 #PROMPT_SHOW_GIT_STATUS=1
 #
+# Timeout in seconds for git diff and git rev-list operations.
+# If exceeded, the prompt displays git:<branch>? instead of full status.
+#PROMPT_GIT_TIMEOUT=2
+#
 # Show Conda environment name at the end of the top bar when active.
 #PROMPT_SHOW_CONDA=1
 #