Clarified what variables in the parser class are meant to be configurable and which are not.
Clarified what variables in the parser class are meant to be configurable and which are not.

MWDelaney/bootstrap-3-shortcodes,Kapeli/php-markdown,queirozfcom/php-markdown-with-syntax-highlight,MWDelaney/bootstrap-3-shortcodes,filipstefansson/bootstrap-3-shortcodes,MWDelaney/bootstrap-3-shortcodes,robbieaverill/php-markdown,jockchou/php-markdown,n054/php-markdown,nazar-pc/php-markdown-next,filipstefansson/bootstrap-3-shortcodes,ashur/php-markdown,mariokonrad/php-markdown,itafroma/php-markdown