add TeraChem

[euhruska]

Updated src/data/codes.json file.

[ltalirz]

Thanks @euhruska for adding TeraChem!

Indeed, TeraChem is on the top of the watchlist, and if one just uses the keyword "TeraChem" it does match the relevance criterion. For other codes in the list, we also add an author or the company, and "terachem" Martinez OR "PetaChem" currently falls slightly short of 100 hits.
See this post for a brief explanation of the status quo.

I suggest we keep this PR open for the moment; if we go towards dropping the author names from the query we can merge it (or we might merge it in 2022 when also the above query will likely cross the threshold).

[ltalirz]

Rebased in #102