Clarify that Twine::toVector *appends* the Twine to the given SmallString.

That's the way it works now, since toVector does not clear the given
SmallString before printing to it.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235000 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed