Fixed standard name aliases

[japamment]

Fixed missing aliases for net_productivity_of_biomass_expressed_as_carbon names in versions 27 - 30 of standard name table.

[rhattersley]

Merge branch 'master' of github.com:cf-convention/cf-convention.githu… …

It's not a good idea to include merge commits in your pull request (PR) - it obscures the real nature of your proposed change.

Also, I note this PR has come directly from your master branch - that can make life complicated (e.g. your fork's "master" branch won't be the same as the original's, and you can't create two PRs at the same time). It'd be better to create each PR from its own branch. The GitHub guides Understanding the GitHub Flow and Hello world give a good introduction to this way of working.

[japamment]

I'm closing this request because I am now able to push to the repository.