Added description of invariant.load metadata to LangRef.  It was added to the compiler in r144100
Added description of invariant.load metadata to LangRef.  It was added to the compiler in r144100

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@150257 91177308-0d34-0410-b5e6-96231b3b80d8

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