build: apple-clang-15 support added

docs/getting_started/installation_and_usage.md

@@ -18,6 +18,7 @@
         - please note that we observed some ICEs on gcc-11
         - no problems with gcc-12.2+
     - clang-16
+    - apple-clang-15
 
 
 ## Repository Structure and Dependencies

docs/index.md

@@ -37,3 +37,4 @@ The library source code is hosted on [GitHub](https://github.com/mpusz/mp-units)
         - please note that we observed some ICEs on gcc-11
         - no problems with gcc-12.2+
     - clang-16
+    - apple-clang-15