Update src/cloud/docker/docker-extend.md

Co-authored-by: Barny Shergold <[email protected]>

Author: arhiopterecs

src/cloud/docker/docker-extend.md

@@ -113,7 +113,7 @@ To add a new PHP extension:
 
   In this case, the `bcmath` extension installs from `docker-php-source` for all `PHP` versions starting from `7.0`.
 
-  In case of installing an extension from `PECL` which has a dependency on a specific package:
+  In the case of installing an extension from `PECL` which has a dependency on a specific package:
   ```php?start_inline=1
    'gnupg' => [
      '>=7.0' => [