Fix erroneous name of the variable in the KB: replicate-annotate-rows-events should be replicate-annotate-row-events

replicate-annotate-rows-events does not work, replicate-annotate-row-events does.

I found 3 pages where it needs to be fixed:

https://kb.askmonty.org/en/server-system-variables/
https://kb.askmonty.org/en/annotate_rows_log_event/
https://kb.askmonty.org/en/mysqld-options-full-list/

I can fix it myself, but need to check with Kristian first that it's just a typo (that is, there was no version where the variable had the other name)