[llvm] [llvm] Proofread ProgrammersManual.rst (PR #150787)

[Tim Gymnich via llvm-commits]

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@@ -1908,38 +1908,38 @@ llvm/ADT/StringRef.h
 The StringRef class is a simple value class that contains a pointer to a
 character and a length, and is quite related to the :ref:`ArrayRef
 <dss_arrayref>` class (but specialized for arrays of characters).  Because
-StringRef carries a length with it, it safely handles strings with embedded nul
+``StringRef`` carries a length with it, it safely handles strings with embedded nul
 characters in it, getting the length does not require a strlen call, and it even
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tgymnich wrote:

```suggestion
characters in it, getting the length does not require a ``strlen`` call, and it even
```

https://github.com/llvm/llvm-project/pull/150787