extract method for parsing manpage header
extract method for parsing manpage header

cesarmarinhorj/asciidoctor,gjtorikian/asciidoctor,gjtorikian/asciidoctor,benignbala/asciidoctor,cuit-zhaxin/asciidoctor,asciidocfx/asciidoctor,yukisan/asciidoctor,yukisan/asciidoctor,glamouracademy/asciidoctor,benignbala/asciidoctor,neontapir/asciidoctor,anthonny/asciidoctor,pepijnve/asciidoctor,glamouracademy/asciidoctor,cuit-zhaxin/asciidoctor,mjang/mj-asciidoc,anthonny/asciidoctor,mjang/mj-asciidoc,asciidocfx/asciidoctor,pepijnve/asciidoctor,neontapir/asciidoctor