Rollup merge of rust-lang#75892 - ArekPiekarz:unstable_book_tls_model…

…_typo, r=petrochenkov

Fix typo in TLS Model in Unstable Book

src/doc/unstable-book/src/compiler-flags/tls-model.md

@@ -22,4 +22,4 @@ The TLS data must not be in a library loaded after startup (via `dlopen`).
 but not in a shared library, and is accessed only from that executable.
 
 `rustc` and LLVM may use a more optimized model than specified if they know that we are producing
-and executable rather than a library, or that the `static` item is private enough.
+an executable rather than a library, or that the `static` item is private enough.