[llvm] [llvm-lit] Print environment variables when using env without subcommand (PR #98414)

[James Henderson via llvm-commits]

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@@ -1,8 +1,10 @@
-# Check for simple one environment variable setting
+## Tests env command for setting single and multiple environment variables.
+
+## Check for simple one environment variable setting
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jh7370 wrote:

Nit: here and below, missing trailing "."

https://github.com/llvm/llvm-project/pull/98414