docs: fix heading levels (backport release-3.2.x) (#14594)

Co-authored-by: J Stickler <julie.stickler@grafana.com>

docs/sources/release-notes/v3-1.md

@@ -77,19 +77,18 @@ Out of an abundance of caution, we advise that users with Loki or Grafana Enterp
 
 ## Bug fixes
 
-## 3.1.2 (2024-10-17)
+### 3.1.2 (2024-10-17)
 
 - **config:** Copy Alibaba and IBM object storage configuration from common ([#14316](https://github.com/grafana/loki/issues/14316)) ([7184d45](https://github.com/grafana/loki/commit/7184d45d8e080874feea8bfd223dedf5f20d3836)).
 - **docker-compose:** upgrade loki and grafana production image tags to 3.1.1 ([#14025](https://github.com/grafana/loki/issues/14025)) ([36fe29e](https://github.com/grafana/loki/commit/36fe29eb334d8300265ca437c0acb423a01c5041)).
 - **logql:** updated JSONExpressionParser not to unescape extracted values if it is JSON object. (backport release-3.1.x) ([#14503](https://github.com/grafana/loki/issues/14503)) ([759f9c8](https://github.com/grafana/loki/commit/759f9c8525227bb1272771a40429d12e015874d9)).
 - **promtail:** Revert build image to Debian Bullseye to fix libc version issue in Promtail ([#14387](https://github.com/grafana/loki/issues/14387)) ([05b6a65](https://github.com/grafana/loki/commit/05b6a65f8bf00b880f17465553b1adaf0cf56d60)).
 - **storage:** have GetObject check for canceled context (backport release-3.1.x) ([#14421](https://github.com/grafana/loki/issues/14421)) ([f3d69ff](https://github.com/grafana/loki/commit/f3d69ffa960c91c0239436a32bb0aa578c0f022a)).
 
-## 3.1.1 (2024-08-08)
+### 3.1.1 (2024-08-08)
 
 - **deps:** Bumped dependencies versions to resolve CVEs ([#13789](https://github.com/grafana/loki/issues/13789)) ([34206cd](https://github.com/grafana/loki/commit/34206cd2d6290566034710ae6c2d08af8804bc91)).
 
-
 ### 3.1.0 (2024-07-02)
 
 - **blooms:** Fix duplicate enqueue item problem in bloom download queue when do sync download ([#13114](https://github.com/grafana/loki/issues/13114)) ([f98ff7f](https://github.com/grafana/loki/commit/f98ff7f58400b5f5a425fae003fb959bfb8c6454)).
@@ -191,4 +190,3 @@ With this fix, if the `max_line_size` config in Promtail has a value, the docker
 - Use to the proper config names in warning messages ([#12114](https://github.com/grafana/loki/issues/12114)) ([4a05964](https://github.com/grafana/loki/commit/4a05964d5520d46d149f2a4e4709eee36c7fb418)).
 - **workflows:** Use an intermediate env variable in GitHub workflow ([#12905](https://github.com/grafana/loki/issues/12905)) ([772616c](https://github.com/grafana/loki/commit/772616cd8f5cbac70374dd4a53f1714fb49a7a3b)).
 - **workflows:** Don't run metric collector on forks ([#12687](https://github.com/grafana/loki/issues/12687)) ([7253444](https://github.com/grafana/loki/commit/72534449a07cd9f410973f2d01772024e8e4b7ba)).
-