Add docstring for fzf_history

Author: kastiglione

lldb/examples/python/fzf_history.py

@@ -8,6 +8,7 @@
 
 @lldb.command()
 def fzf_history(debugger, cmdstr, ctx, result, _):
+    """Use fzf to search and select from lldb command history."""
     if sys.platform != "darwin":
         result.SetError("fzf_history supports macOS only")
         return