[clang-tools-extra] [clang-tidy] Add readability-use-span-first-last check (PR #118074)

[Helmut Januschka via cfe-commits]

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@@ -0,0 +1,24 @@
+.. title:: clang-tidy - readability-use-span-first-last
+
+readability-use-span-first-last
+===============================
+
+Checks for uses of ``std::span::subspan()`` that can be replaced with clearer
+``first()`` or ``last()`` member functions. These dedicated methods were added 
+to C++20 to provide more expressive alternatives to common subspan operations.
+
+Covered scenarios:
+
+========================== ====================
----------------
hjanuschka wrote:

rst formatting is really tough 😬

https://github.com/llvm/llvm-project/pull/118074