Redundant empty-anchored links

Many links in the wiki are repeated, with the second link having empty anchor text:

The macros `MK_SMALL_BITMAP`, `BITMAP_SIZE`, and `BITMAP_BITS` in [InfoTables.h](https://gitlab.haskell.org/ghc/ghc/tree/master/includes/rts/storage/InfoTables.h)[](/trac/ghc/export/HEAD/ghc/includes/rts/storage/InfoTables.h) pro

We should drop the second link