Add apple-clang 11 to settings.yml (conan-io#1327)

Signed-off-by: Uilian Ries <uilianries@gmail.com>

Author: uilianries

reference/config_files/settings.yml.rst

@@ -79,7 +79,7 @@ are possible. These are the **default** values, but it is possible to customize
             libcxx: [libstdc++, libstdc++11, libc++, c++_shared, c++_static]
             cppstd: [None, 98, gnu98, 11, gnu11, 14, gnu14, 17, gnu17, 20, gnu20]
         apple-clang:
-            version: ["5.0", "5.1", "6.0", "6.1", "7.0", "7.3", "8.0", "8.1", "9.0", "9.1", "10.0"]
+            version: ["5.0", "5.1", "6.0", "6.1", "7.0", "7.3", "8.0", "8.1", "9.0", "9.1", "10.0", "11.0"]
             libcxx: [libstdc++, libc++]
             cppstd: [None, 98, gnu98, 11, gnu11, 14, gnu14, 17, gnu17, 20, gnu20]
         qcc: