Rename var `rsJoiner` to `rsOptJoin` to align with others.
Rename var `rsJoiner` to `rsOptJoin` to align with others.

tonyonodi/lodash,steelsojka/lodash,beaugunderson/lodash,msmorgan/lodash,rlugojr/lodash,rlugojr/lodash,steelsojka/lodash,Xotic750/lodash,beaugunderson/lodash,boneskull/lodash,msmorgan/lodash,boneskull/lodash,tonyonodi/lodash,Xotic750/lodash,Xotic750/lodash