[predefined-counter-styles] Joining letters put in wrong position in the comments

behnam has just created a new issue for 
https://github.com/w3c/predefined-counter-styles:

== Joining letters put in wrong position in the comments ==
In Perso-Arabic script, letter HEH needs to be *followed by* a ZWJ 
(U+200D) to be *shaped* correctly for its *standalone* form.

In the comment lines in `persian-abjad` and `persian-alphabetic`, 
because of the `<bdo dir="ltr">` tag, ZWJ is being affected after the 
HEH.

We need to fix this somehow, but it's not hi-pri.

See https://github.com/w3c/predefined-counter-styles/issues/2