[wwwdocs] Add branch description for new branch unified-autovect

[Sameera Deshpande]

Hi!

I have created new branch unified-autovect based on ToT.

Please find attached the patch adding information about new branch 
"unified-autovect" in the documentation.
Is it ok to commit?

- Thanks and regards,
  Sameera D.

unified-autovec-doc.patch
Description: unified-autovec-doc.patch