Update the project name in README.txt

Per llvm.org: "The name "LLVM" itself is not an acronym; it is the full
name of the project."

Differential Revision: https://reviews.llvm.org/D47796

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334087 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed