Clarify parsing rules for span directives
Matches of spans between two styling directives MUST contain some text - between the two styling directives and the opening styling directive - MUST be located at the beginning of the line, after a whitespace - character, or after a different opening styling directive. + between the two styling directives, otherwise neither directive is valid. + The opening styling directive MUST be located at the beginning of the + line, after a whitespace character, or after a different opening styling + directive. The opening styling directive MUST NOT be followed by a whitespace character and the closing styling directive MUST NOT be preceeded by a whitespace character. @@ -413,6 +420,7 @@