Adding changelog and changelog verifier (opensearch-project#92)

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

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

.github/workflows/changelog_verifier.yml

@@ -0,0 +1,18 @@
+name: "Changelog Verifier"
+on:
+  pull_request:
+    types: [opened, edited, review_requested, synchronize, reopened, ready_for_review, labeled, unlabeled]
+
+jobs:
+  # Enforces the update of a changelog file on every pull request
+  verify-changelog:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          ref: ${{ github.event.pull_request.head.sha }}
+
+      - uses: dangoslen/changelog-enforcer@v3
+        with:
+          skipLabels: "autocut"

.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'

CHANGELOG.md

@@ -0,0 +1,19 @@
+# CHANGELOG
+Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
+
+## [Unreleased]
+### Added
+- Github workflow for changelog verification ([#92](https://github.com/opensearch-project/opensearch-php/pull/92))
+
+### Changed
+
+### Deprecated
+
+### Removed
+
+### Fixed
+
+### Security
+
+
+[Unreleased]: https://github.com/opensearch-project/opensearch-php/compare/2.0...HEAD

CONTRIBUTING.md

@@ -7,8 +7,9 @@
 - [Developer Certificate of Origin](#developer-certificate-of-origin)
 - [License Headers](#license-headers)
   - [Java](#java)
-  - [Python](#python)
-  - [Shell](#shell)
+  - [Python, Ruby, Shell](#python-ruby-shell)
+- [Changelog](#changelog)
+  - [Adding Changes](#adding-changes)
 - [Review Process](#review-process)
 
 ## Contributing to OpenSearch
@@ -98,20 +99,39 @@ New files in your code contributions should contain the following license header
 /*
  * Copyright OpenSearch Contributors
  * SPDX-License-Identifier: Apache-2.0
- */
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ *
+*/
 ```
 
-### Python
+### Python, Ruby, Shell
 ```
 # Copyright OpenSearch Contributors
 # SPDX-License-Identifier: Apache-2.0
+#
+# The OpenSearch Contributors require contributions made to
+# this file be licensed under the Apache-2.0 license or a
+# compatible open source license.
 ```
 
-### Shell
-```
-# Copyright OpenSearch Contributors
-# SPDX-License-Identifier: Apache-2.0
-```
+## 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.
+
+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
+
+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.
+
+Adding in the change is a two step process -
+1. Add your changes to the corresponding section within the CHANGELOG file with dummy pull request information, publish the PR.
+
+2. Update the entry for your change in [`CHANGELOG.md`](CHANGELOG.md) and make sure that you reference the pull request there.
 
 ## Review Process