add note to README about not being able to combine inline HTML with syntax highlighting [skip ci]
add note to README about not being able to combine inline HTML with syntax highlighting [skip ci]

Hextremist/asciidoctor-pdf,dsisnero/asciidoctor-pdf,asciidoctor/asciidoctor-pdf,asciidoctor/asciidoctor-pdf,mojavelinux/asciidoctor-pdf,Hextremist/asciidoctor-pdf,dsisnero/asciidoctor-pdf,mojavelinux/asciidoctor-pdf