Gists don't have a friendly interface to merge up and down request. I assume the OP wants other people to share and contribute to his list.
Also Its been the meta to use a Github repository.
Also Its been the meta to use a Github repository.
The sense you mean is a shortening of “metagame”, a term used since the early 2000s or maybe before by Starcraft I players to describe the broad trends in overall strategy and play-style evolving over time as the whole community of players adapt to each-other’s games. The term may have been used in other similar contexts before that time, but as far as I can tell that’s mainly where it was popularized.
So is your description, Meta is an ancient greek preposition that in English roughly means a concept that is an abstraction from another concept (though originally in Greek meant "after").
It is also used commonly to mean something that is knowingly circular or self-referential "That film director doing a movie about film directors was so meta", I don't like this usage but it is common.
In either case your usage is considerably narrower and not at all the standard usage.
It's reasonable for the term metagame to encompass the evolution of the strategy of a game over the years (character matchups in fighting games, use of certain "builds" in real-time strategy, etc.), as it's beyond the scope of individual matches or players; it's then reasonable to abbreviate that to "meta", as many gaming communities do, and applying it to long-term trends in things other than games is only a small semantic shift.
Of course, that means little if the term doesn't actually exist here, but if it could come to exist without any especially gross abuse of language, I wouldn't call it wrong.
He's saying "oh, this person just used meta like it means 'something that is all the rage', which is some strange emergent usage from a gaming subculture. I'd better explain that so it makes any sense at all."
I would imagine most people here know what the word meta actually means, so just saying "this isn't standard usage" is sufficient.