reccomend the llvm-project source archive that has a signature, instead of the github generated zip

Author: DavidSpickett

llvm/utils/release/github-upload-release.py

@@ -61,7 +61,7 @@ def create_release(repo, release, tag=None, name=None, message=None):
 
 In addition, source archives are available:
 * `<sub-project>*.src.tar.xz` are archives of the sources of specific sub-projects of `llvm-project` (except for `test-suite` which is an archive of the [LLVM Test Suite](https://github.com/llvm/llvm-test-suite)).
-* To get all the `llvm-project` source code for this release, choose the one of the `Source Code` archives.
+* To get all the `llvm-project` source code for this release, choose `llvm-project-{release}.src.tar.xz`.
 
 ## Verifying Packages