added a cache for the php documentation in CI workflow

Author: Kharhamel

.github/workflows/continuous-integration.yml

@@ -33,14 +33,23 @@ jobs:
  coverage: "pcov"
  php-version: "${{ matrix.php-version }}"
 
+ - name: "Cache the php documentation"
+ id: cache-php-doc
+ uses: "actions/cache@v1"
+ with:
+ path: "generator/doc/doc-en"
+ key: "php-doc"
+
  - name: "Check out salathe/phpdoc-base"
  uses: "actions/checkout@v2"
+ if: steps.cache-php-doc.outputs.cache-hit != 'true'
  with:
  path: "generator/doc/doc-en/doc-base"
  repository: "salathe/phpdoc-base"
 
  - name: "Check out php/doc-en"
  uses: "actions/checkout@v2"
+ if: steps.cache-php-doc.outputs.cache-hit != 'true'
  with:
  path: "generator/doc/doc-en/en"
  repository: "php/doc-en"