Revised org.springframework.lang javadoc

Issue: SPR-15756

spring-core/src/main/java/org/springframework/lang/package-info.java

@@ -1,8 +1,10 @@
 /**
- * Annotations indicating the use of core Java/JDK API beyond the API level of JDK 6 update 18.
- * Used descriptively within the framework codebase; validated by Animal Sniffer at build time.
+ * Common annotations with language-level semantics: nullability as well as JDK API indications.
+ * These annotations sit at the lowest level of Spring's package dependency arrangement, even
+ * lower than {@code org.springframework.util}, with no Spring-specific concepts implied.
+ *
+ * <p>Used descriptively within the framework codebase. Can be validated by build-time tools
+ * (e.g. FindBugs or Animal Sniffer), alternative JVM languages (e.g. Kotlin), as well as IDEs
+ * (e.g. IntelliJ IDEA or Eclipse with corresponding project setup).
  */
-@NonNullApi
-@NonNullFields
 package org.springframework.lang;
-