Drop the local [BIDI] reference

It has been merged into specref:
https://github.com/tobie/specref/pull/141
Refer to DOM as a standard

For consistency with Encoding/HTML and because DOM calls itself a standard.
Merge pull request #164 from foolip/dom-standard

Refer to DOM as a standard
Merge pull request #163 from foolip/bidi-ref

Drop the local [BIDI] reference