fix TOC links with leading punctuation

Author: rmosolgo

guides/_plugins/api_doc.rb

@@ -105,7 +105,11 @@ def render(context)
           #{headers.map do |h|
               depth = h.count("#")
               text = h.gsub(/^#+ /, "")
-              target = text.downcase.gsub(/[^a-z0-9]+/, "-").sub(/-$/, "")
+              target = text.downcase
+                .gsub(/[^a-z0-9]+/, "-")
+                .sub(/-$/, "")
+                .sub(/^-/, "")
+
               rendered_text = Kramdown::Document.new(text, auto_ids: false)
                 .to_html
                 .sub("<p>", "")