doc for string methods using char agrs

Author: maumar

entity-framework/core/what-is-new/ef-core-10.0/whatsnew.md

@@ -74,6 +74,16 @@ var query = context.Students
 
 See [#12793](https://github.com/dotnet/efcore/issues/12793) and [#35367](https://github.com/dotnet/efcore/issues/35367) for more details.
 
+<a name="support-string-functions-with-char-args"></a>
+
+### Support for some string functions taking `char` as arguments
+
+EF Core 10 introduces support for several string function overloads that accept `char` arguments. Previously, EF Core only recognized overloads accepting `string` arguments, which limited options for developers working with single-character parameters in string functions.
+
+Here are the new overloads than can now be used in queries: [`IndexOf(char)`](/dotnet/api/system.string.indexof?view=net-9.0#system-string-indexof(system-char)), [`IndexOf(char, int)`](/dotnet/api/system.string.indexof?view=net-9.0#system-string-indexof(system-char-system-int32)), [`Replace(char, char)`](/dotnet/api/system.string.replace?view=net-9.0#system-string-replace(system-char-system-char)), [`Contains(char)`](/dotnet/api/system.string.contains?view=net-9.0#system-string-contains(system-char)), [`Contains(char, StringComparison)`](/dotnet/api/system.string.contains?view=net-9.0#system-string-contains(system-char-system-stringcomparison)), [`StartsWith(char)`](/dotnet/api/system.string.startswith?view=net-9.0#system-string-startswith(system-char)), [`EndsWith(char)`](/dotnet/api/system.string.endswith?view=net-9.0#system-string-endswith(system-char)).
+
+Thanks to [@ChrisJollyAU](https://github.com/ChrisJollyAU) for implementing this change (in [#34999](https://github.com/dotnet/efcore/pull/34999)).
+
 <a name="other-query-improvements"></a>
 
 ### Other query improvements