[docs] Fix title overline.

mkurdej · mkurdej · commit b2be167a4952 · 2021-05-03T18:32:36.000+02:00
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
@@ -1,4 +1,4 @@
-=========================================
+========================================
 Clang 13.0.0 (In-Progress) Release Notes
 ========================================
 

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-=========================================`
	`1`	`+========================================`
`2`	`2`	`Clang 13.0.0 (In-Progress) Release Notes`
`3`	`3`	`========================================`
`4`	`4`