assisted digital changes

Could someone double check embedded YouTube video in action-plan.md
please? Video does not play on page, but is correct link. Thanks.

- Added document for service managers
- Updated two links
Only exclude the root vendor folder

Excluding all directories named vendor was excluding the vendor
directory in the toolkit, which is where the jQuery that plays
videos lives.
Tidy up Jekyll exclusions

- lint.go is now in tools/
- Only exclude the root /tools directory
Merge pull request #396 from alphagov/assisted-digital

assisted digital changes