Fix broken asciidoc heading

ttddyy · jhoeller · commit dacda5859acc · 2019-04-06T11:02:45.000+02:00
diff --git a/src/docs/asciidoc/core/core-null-safety.adoc b/src/docs/asciidoc/core/core-null-safety.adoc
@@ -1,4 +1,4 @@
-[-[null-safety]]
+[[null-safety]]
 = Null-safety
 
 Although Java does not let you express null-safety with its type system, the Spring Framework

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-[-[null-safety]]`
	`1`	`+[[null-safety]]`
`2`	`2`	`= Null-safety`
`3`	`3`
`4`	`4`	`Although Java does not let you express null-safety with its type system, the Spring Framework`