Update README.md

Author: mshinwell

README.md

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+# ocaml-flambda/llvm-project
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+This repository is currently for development of a version of lldb that works well in conjunction with the flambda-backend compiler.  The `main` branch is being used here, but this isn't quite the same as the upstream `main` branch: it is based off a recent LLVM release to ensure everything compiles.
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 # The LLVM Compiler Infrastructure
 
 This directory and its sub-directories contain source code for LLVM,