Add Hash-tag links for lexical structure definitions and anchor tags for reference #172
Description
Firstly, it would be good to update all lexical BNF definitions with hash-tag links such that all definitions have their names wrapped in span that the name as the id, <span id="decls">decls</span> = ..., and anchors would then wrap all occurrences `decls'.
Secondarily, it would be nice if the full names of each of these definitions could occurs as a popup after hovering over them such as, `decls' and decls
Finally, it would be nice if there was a page, could be auto generated, that sorted the lexical definitions in forward and reverse order of dependencies. Also, it would be good if such definitions were wrapped in an anchor point to the part of the section of the report they were defined in: <a href="https://www.haskell.org/onlinereport/haskell2010/haskellch4.html"><span href="..." title="...">decls</span></a>