Enhancement: Clarify maxbodylength messaging

[mcandre]

There are many ways to calculate the length of some text. Bytes, characters, runes, words, lines...

I think the maxbodylength rule operates on lines, but the current warning string format does not appear to say this explicitly. Can we please add the word "line" just before "length" in the output?

[MattOates]

It doesn't operate on lines, it operates on parsed/tokenised Make commands, so a single shell thats got a tonne of continuations and semicolons counts as a single "line". Which actually makes this feature especially irritating as it ignores the 500 lines of shell in a phony but complains if you have a 3 line target with some echo statements.