Mistake in malleability type table for `thresh`

[benma]

The malleability type properties for thresh on the website state:

s=at most k-1 are non-s; e=all are s

for e it should say e=all are e and all are s. The code implements it like this too:

https://github.com/sipa/miniscript/blob/484386a50dbda962669cc163f239fe16e101b6f0/bitcoin/script/miniscript.cpp#L241