[text.encoding.overview] Use same parameter names as detailed description (#6768)

Author: jwakely

source/locales.tex

@@ -4701,8 +4701,8 @@
     struct aliases_view;
     constexpr aliases_view aliases() const noexcept;
 
-    friend constexpr bool operator==(const text_encoding& encoding,
-                                     const text_encoding& other) noexcept;
+    friend constexpr bool operator==(const text_encoding& a,
+                                     const text_encoding& b) noexcept;
     friend constexpr bool operator==(const text_encoding& encoding, id i) noexcept;
 
     static consteval text_encoding literal() noexcept;