Doc comment for `run_optimize` does not match CRoaring's doc comment for the same

[Dr-Emann]

The documentation for roaring_bitmap_run_optimize found here says:

Returns true if the result has at least one run container.

But the docs in the croaring crate state:

Compresses of the bitmap. Returns true if the bitmap was modified.

We're a thin wrapper around CRoaring, our run_optimize function is just a thin wrapper around CRoaring's roaring_bitmap_run_optimize.

croaring-rs/croaring/src/bitmap/imp.rs

Lines 1119 to 1121 in fa3bff4

	pub fn run_optimize(&mut self) -> bool {
	unsafe { ffi::roaring_bitmap_run_optimize(&mut self.bitmap) }
	}

Need to determine which doc comment is correct, (assuming it's CRoaring's) and fix the comment.

Originally posted by @lucascool12 in RoaringBitmap/roaring-rs#320 (comment)