Docs typos and diction errors

[proofer]

My github moniker derives from my proofreading activities. The initial entry in this discussion:

readmes/mini-clue.md (2 instances); doc/mini-clue.txt (3 instances); doc/mini-clue.txt (same 3):
full proof -> foolproof -- "foolproof" is a single word meaning "incapable of going wrong or being misused".

[echasnovski]

Thanks, I learned something new today :)
I'll fix this soon.

Edit: Should be fixed on latest main.