Fix heading rules

level1: # v1.xx
level 2: ## Release v1.xx.y - YYYY/MM/DD

Signed-off-by: Kentaro Hayashi <hayashi@clear-code.com>

CHANGELOG.md

@@ -1,4 +1,4 @@
-# v1.14.5
+# v1.14
 
 ## Release v1.14.5 - 2022/02/09
 
@@ -22,8 +22,6 @@
 * Fix "ArgumentError: unknown keyword: :logger" on Windows with Ruby 3.1
   https://github.com/fluent/fluentd/pull/3592
 
-# v1.14.4
-
 ## Release v1.14.4 - 2022/01/06
 
 ### Enhancement
@@ -41,8 +39,6 @@
   https://github.com/fluent/fluentd/pull/3574
   https://github.com/fluent/fluentd/pull/3577
 
-# v1.14.3
-
 ## Release v1.14.3 - 2021/11/26
 
 ### Enhancement
@@ -71,8 +67,6 @@
   newer version is required to implement additional `fluent-ctl` commands.
   https://github.com/fluent/fluentd/pull/3556
 
-# v1.14.2
-
 ## Release v1.14.2 - 2021/10/29
 
 IMPORTANT: This release contain the fix for CVE-2021-41186 -
@@ -92,8 +86,6 @@ We recommend to upgrade Fluentd to v1.14.2 or use patched version of
 * Fixed ReDoS vulnerability in parser_apache2.
   This vulnerability is caused by a certain pattern of a broken apache log.
 
-# v1.14.1
-
 ## Release v1.14.1 - 2021/09/29
 
 ### Enhancement
@@ -123,8 +115,6 @@ We recommend to upgrade Fluentd to v1.14.2 or use patched version of
   next_retry_seconds -> next_retry_time)
   https://github.com/fluent/fluentd/pull/3518
 
-# v1.14.0
-
 ## Release v1.14.0 - 2021/08/30
 
 ### Enhancement
@@ -167,7 +157,7 @@ We recommend to upgrade Fluentd to v1.14.2 or use patched version of
   https://github.com/fluent/fluentd/pull/3479
   https://github.com/fluent/fluentd/pull/3484
 
-# v1.13.3
+# v1.13
 
 ## Release v1.13.3 - 2021/07/27
 
@@ -189,10 +179,6 @@ We recommend to upgrade Fluentd to v1.14.2 or use patched version of
 * Remove needless spaces in a sample config file
   https://github.com/fluent/fluentd/pull/3456
 
-### Enhancement
-
-# v1.13.2
-
 ## Release v1.13.2 - 2021/07/12
 
 ### Enhancement
@@ -228,8 +214,6 @@ We recommend to upgrade Fluentd to v1.14.2 or use patched version of
   by security scanning tools.
   https://github.com/fluent/fluentd/pull/3450
 
-# v1.13.1
-
 ## Release v1.13.1 - 2021/06/25
 
 ### Bug fix
@@ -254,8 +238,6 @@ We recommend to upgrade Fluentd to v1.14.2 or use patched version of
 * CI: Dropped to run CI for Ruby 2.5
   https://github.com/fluent/fluentd/pull/3412
 
-# v1.13
-
 ## Release v1.13.0 - 2021/05/29
 
 ### Enhancement