Polish wording in reference manual

Author: sbrannen

framework-docs/modules/ROOT/pages/core/aot.adoc

@@ -167,7 +167,7 @@ Kotlin::
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-WARNING: Kotlin class names with backticks using invalid Java identifiers (not starting by a letter, containing spaces, etc.) are not supported.
+WARNING: Kotlin class names with backticks that use invalid Java identifiers (not starting with a letter, containing spaces, etc.) are not supported.
 
 Since there isn't any particular condition on this class, `dataSourceConfiguration` and `dataSource` are identified as candidates.
 The AOT engine will convert the configuration class above to code similar to the following: