[llvm] [docs] use "=" in options with arguments (PR #142340)

[Nikita Popov via llvm-commits]

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@@ -112,7 +112,7 @@ OUTPUT OPTIONS
 
  Enable -v, but for all tests not just failed tests.
 
-.. option:: -o PATH, --output PATH
+.. option:: -o=PATH, --output=PATH
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nikic wrote:

Hm, `-o=PATH` looks quite unusual.

https://github.com/llvm/llvm-project/pull/142340