Fix typo in docstring

dotfiles/bash/main.bashrc

     # Edit text in primary clipboard and save it to C-C clipboard
     #
     # Ideal for editing snippets in browser-based editors: during editing,
-    # select the text, open terminal, call `xvx`, edit the text, move
+    # select the text, open terminal, call `xvxx`, edit the text, move
     # back to the browser and paste it over the old (still selected) text.
     # That's it, no need to make up and save temporary files.
     #