Adding dependabot changelog PR workflow

Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>

.github/workflows/dependabot_pr.yml

@@ -0,0 +1,37 @@
+name: Dependabot PR actions
+on: pull_request
+
+jobs:
+  dependabot:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+      contents: write
+    if: ${{ github.actor == 'dependabot[bot]' }}
+    steps:
+      - name: GitHub App token
+        id: github_app_token
+        uses: tibdex/github-app-token@v1.5.0
+        with:
+          app_id: ${{ secrets.APP_ID }}
+          private_key: ${{ secrets.APP_PRIVATE_KEY }}
+          installation_id: 22958780
+
+      - name: Check out code
+        uses: actions/checkout@v2
+        with:
+          token: ${{ steps.github_app_token.outputs.token }}
+
+      - name: Update the changelog
+        uses: dangoslen/dependabot-changelog-helper@v1
+        with:
+          version: 'Unreleased'
+
+      - name: Commit the changes
+        uses: stefanzweifel/git-auto-commit-action@v4
+        with:
+          commit_message: "Update changelog"
+          branch: ${{ github.head_ref }}
+          commit_user_name: dependabot[bot]
+          commit_user_email: support@github.com
+          commit_options: '--signoff'

CONTRIBUTING.md

@@ -9,7 +9,7 @@
   - [Java](#java)
   - [Python, Ruby, Shell](#python-ruby-shell)
 - [Changelog](#changelog)
-  - [Adding changes](#adding-changes)
+  - [Adding Changes](#adding-changes)
 - [Review Process](#review-process)
 
 ## Contributing to OpenSearch
@@ -119,12 +119,12 @@ New files in your code contributions should contain the following license header
 
 ## Changelog
 
-OpenSearch-PHP maintains a version specific changelog by enforcing a change to the ongoing [CHANGELOG](CHANGELOG.md) file adhering to the [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) format.
+OpenSearch-php maintains a version specific changelog by enforcing a change to the ongoing [CHANGELOG](CHANGELOG.md) file adhering to the [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) format.
 
 The changes are curated by version, with the changes to the main branch added chronologically to the `Unreleased` version. Each version has corresponding sections which list out the category of the change - `Added`, `Changed`, `Deprecated`, `Removed`, `Fixed`, `Security`.
 
 
-### Adding changes
+### Adding Changes
 
 As a contributor, you must ensure that every pull request has its changes listed out within the corresponding version and appropriate section of the [CHANGELOG](CHANGELOG.md) file.