Add Github workflow for khoj.el build and quality checks

Add khoj.el build badge to khoj.el Readme

.github/workflows/build_khoj_el.yml

@@ -0,0 +1,39 @@
+# melpa quality checks like checkdoc, byte-compile, package-lint for khoj.el
+# using melpazoid: https://github.com/riscy/melpazoid
+
+name: build khoj.el
+on:
+  push:
+    branches:
+      - 'master'
+    paths:
+      - src/interface/emacs/*.el
+      - .github/workflows/build_khoj_el.yml
+  pull_request:
+    branches:
+      - 'master'
+    paths:
+      - src/interface/emacs/*.el
+      - .github/workflows/build_khoj_el.yml
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python 3.9
+      uses: actions/setup-python@v1
+      with: { python-version: 3.9 }
+    - name: Install
+      run: |
+        python -m pip install --upgrade pip
+        sudo apt-get install emacs && emacs --version
+        git clone https://github.com/riscy/melpazoid.git ~/melpazoid
+        pip install ~/melpazoid
+    - name: Run
+      env:
+        # Khoj recipe from https://github.com/melpa/melpa/pull/8321/files
+        RECIPE: (khoj :fetcher github :repo "debanjum/khoj" :files ("src/interface/emacs/*.el"))
+        EXIST_OK: true
+        LOCAL_REPO: ${{ github.workspace }}
+      run: echo $GITHUB_REF && make -C ~/melpazoid

src/interface/emacs/README.org

@@ -1,5 +1,5 @@
 * Khoj Emacs 🦅
-  [[https://stable.melpa.org/#/khoj][file:https://stable.melpa.org/packages/khoj-badge.svg]] [[https://melpa.org/#/khoj][file:https://melpa.org/packages/khoj-badge.svg]]
+  [[https://stable.melpa.org/#/khoj][file:https://stable.melpa.org/packages/khoj-badge.svg]] [[https://melpa.org/#/khoj][file:https://melpa.org/packages/khoj-badge.svg]] [[https://github.com/debanjum/khoj/actions/workflows/build_khoj_el.yml][https://github.com/debanjum/khoj/actions/workflows/build_khoj_el.yml/badge.svg?]]
  
   /Natural language search from within Emacs using [[https://github.com/debanjum/khoj][Khoj]]/