8340680: Fix typos in javax.lang.model.SourceVersion

Reviewed-by: darcy, iris

Author: Pavel Rappo

src/java.compiler/share/classes/javax/lang/model/SourceVersion.java

@@ -601,7 +601,7 @@ public static boolean isName(CharSequence name, SourceVersion version) {
      * keywords</i>.
      *
      * @param s the string to check
-     * @return {@code true} if {@code s} is a keyword, boolean
+     * @return {@code true} if {@code s} is a keyword, a boolean
      * literal, or the null literal, {@code false} otherwise.
      * @jls 3.9 Keywords
      * @jls 3.10.3 Boolean Literals
@@ -619,7 +619,7 @@ public static boolean isKeyword(CharSequence s) {
      *
      * @param s the string to check
      * @param version the version to use
-     * @return {@code true} if {@code s} is a keyword, boolean
+     * @return {@code true} if {@code s} is a keyword, a boolean
      * literal, or the null literal, {@code false} otherwise.
      * @jls 3.9 Keywords
      * @jls 3.10.3 Boolean Literals