[clang] [clang-repl] adding documentation and information for %commands (PR #150348)

[David Spickett via cfe-commits]

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@@ -370,9 +378,24 @@ int main(int argc, const char **argv) {
       if (Input == R"(%undo)") {
         if (auto Err = Interp->Undo())
           llvm::logAllUnhandledErrors(std::move(Err), llvm::errs(), "error: ");
+      } else if (Input == R"(%help)") {
+        auto Err =
+            llvm::make_error<llvm::StringError>(help_output, std::error_code());
+        llvm::logAllUnhandledErrors(std::move(Err), llvm::errs(), "");
+      } else if (Input == R"(%lib)") {
+        auto Err = llvm::make_error<llvm::StringError>(lib_bad_args,
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DavidSpickett wrote:

Put the string here rather than defining it above.

https://github.com/llvm/llvm-project/pull/150348