Don't store `content` for cite

[jamietanna]

To avoid unnecessary storage overhead (in the case of long posts) as well as potential copyright claims we should remove the content for a context.

That being said, we would want this for a repost so maybe it needs more nuance?

[barryf]

On my website I display a truncated version of the content for a few different types. I did consider the copyright aspect so Vibrancy doesn't store the content on GitHub, just in the contexts table. There's no size limit which could be worth looking at.

[jamietanna]

That's fair :+1: Yeah maybe taking the first ~1000 characters should be plenty?

[barryf]

That should work. I truncate after the first 30 words: https://github.com/barryf/barryfrost/blob/master/src/http/get-catchall/helpers.js#L35