[pr 2702] finishing the @StandardException feature.

* rewritten how it works a bit: Now compatible with parent exceptions that don't have the Throwable variants.
* rewritten how it works a bit: You can now provide the full constructor only; the rest will forward to it.
* fixing up style.
* rewrite the docs.

test/transform/resource/before/StandardExceptions.java

@@ -1,8 +1,9 @@
+import lombok.AccessLevel;
 import lombok.experimental.StandardException;
 
 @StandardException class EmptyException extends Exception {
 }
-@StandardException class NoArgsException extends Exception {
+@StandardException(access = AccessLevel.PROTECTED) class NoArgsException extends Exception {
 	public NoArgsException() {
 	}
 }