Fix typos in x*() docstrings

dotfiles/config/bashum/main.bashrc

@@ -562,7 +562,7 @@ xvxx() {
     # 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.
     #
-    # If you quickly realize you need to re-edit the text, use xvvx().
+    # If you quickly realize you need to re-edit the text, use xxvxx().
     #
     xop o | vipe | xop ii
 }
@@ -616,7 +616,7 @@ vxx() {
     # or another GUI application.  Run the command with `vxx`, edit
     # the text, move back to the application and paste it.
     #
-    # If you quickly realize you need to re-edit the text, use xvvx().
+    # If you quickly realize you need to re-edit the text, use xxvxx().
     #
     vipe | xop ii
 }
@@ -625,7 +625,7 @@ xcxx() {
     #
     # Filter text in primary clipboard using command $@ and save it to C-C clipboard
     #
-    # Similar to xvvx() but instead of interactive editing, provided filter
+    # Similar to xvxx() but instead of interactive editing, provided filter
     # command is run.
     #
     local cmd=("$@")