[clang] [clang] Proofread *.rst (PR #166897)

[Kazu Hirata via cfe-commits]

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@@ -58,7 +58,7 @@ adopt, offering these properties that make it widely adoptable in practice:
 * It has a relatively low adoption cost.
 
 This document discusses the key designs of ``-fbounds-safety``. The document is
-subject to be actively updated with a more detailed specification.
+subject to being actively updated with a more detailed specification.
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kazutakahirata wrote:

Fixed.  Thanks for the review as usual!

https://github.com/llvm/llvm-project/pull/166897