Finds a link reference for
`label` and creates a new link
to it with `content` as the link text. If `label` was not encountered in
the reference-gathering parser pass the label and content are reconstructed
with the linking `text` (usually whitespace).
# File lib/rdoc/markdown.rb, line 697
def link_to content, label = content, text = nil
raise ParseError, 'enable notes extension' if
content.start_with? '^' and label.equal? content
if ref = @references[label] then
"{#{content}}[#{ref}]"
elsif label.equal? content then
"[#{content}]#{text}"
else
"[#{content}]#{text}[#{label}]"
end
end