the formatplus plugin almost does what you want. It uses !!
instead of ,,
. You can easily modify it.
install the plugin, then with a notepad, edit the file lib/plugins/formatplus/syntax/smallcapsplus.php
. do a global search and replace : replace every !!
by ,,
. Save and exit your notepad. Ask your search engine how to clear your browser cache, how to clear DokuWiki cache, purge your browser cache, clear DW cache, you're all set.