Chore (release notes): polish 2.7.0 notes (opensearch-project#3896)

Add welcome/thank you section for first-time contributors
Fix link that pointed to issue instead of PR
Add entry for OUI bump

Signed-off-by: Josh Romero <rmerqg@amazon.com>

release-notes/opensearch-dashboards.release-notes-2.7.0.md

@@ -37,7 +37,7 @@
 - [Table Visualization] Fix data table not adjusting height on the initial load ([#3816](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3816))
 - [Timeline] Fix y-axis label color in dark mode ([#3698](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3698))
 - [TSVB] Fix undefined serial diff aggregation documentation link ([#3503](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3503))
-- [UI] Add clarifying tooltips to header navigation icons ([#3573](https://github.com/opensearch-project/OpenSearch-Dashboards/issues/3573))
+- [UI] Add clarifying tooltips to header navigation icons ([#3626](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3626))
 - [VisBuilder] Fix multiple warnings thrown on page load ([#3732](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3732))
 - [VisBuilder] Fix Firefox legend selection issue ([#3732](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3732))
 - [VisBuilder] Fix type errors ([#3732](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3732))
@@ -70,6 +70,7 @@
 - Allow selecting the Node.js binary using `NODE_HOME` and `OSD_NODE_HOME` ([#3508](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3508))
 - Remove the unused `renovate.json5` file ([#3489](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3489))
 - Bump `styled-components` from `5.3.5` to `5.3.9` ([#3678](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3678))
+- Bump `oui` from `1.0.0` to `1.1.1` ([3884](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3884))
 - [Timeline] Update default expressions from `.es(*)` to `.opensearch(*)`. ([#2720](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/2720))
 
 ### 🪛 Refactoring
@@ -86,3 +87,7 @@
 
 - Update caniuse to `1.0.30001460` to fix failed integration tests ([#3538](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3538))
 - [Tests] Fix unit tests for `get_keystore` ([#3854](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/3854))
+
+## 🎉 Welcome
+
+Thank you to all the first-time contributors who made this release possible: @pjfitzgibbons, @djindjic, @jlabatut, @sayuree, @Nicksqain, @kappassov, @aswath86, @frost017, @curq, @Aigerim-ai, @andreymyssak, @Hailong-am!