Update contributor docs

Author: cytopia

php_modules/README.md

@@ -18,6 +18,8 @@ All PHP modules/extensions (for all PHP versions and both for `amd64` and `arm64
 
 ## How to add PHP modules?
 
+> **Note:** The below listed steps require you to have the following on your local machine installed: `python3`, `PyYAML` Python module, `docker` and `make`.
+
 1. **Inside `php_modules/` directory:**
     1. Create a new directory with the name of the PHP module in `php_modules/`
     2. Add `build.yml`, `options.yml` and `test.yml` into your newly created directory
@@ -28,7 +30,7 @@ All PHP modules/extensions (for all PHP versions and both for `amd64` and `arm64
     2. Run `make gen-dockerfiles` to generate Dockerfiles via Ansible
     3. Run `make build STAGE=mods VERSION=8.1 ARCH=linux/amd64` to build the `mods` Docker image with version `8.1` for platform `linux/amd64`
 
-**Note:** If you want to test if your new module builds correctly, you can generate Dockerfiles which only contain this one module and all others removed. This allows for much faster Docker builds and you don't have to wait for all other modules to be built. To do so, you generate group_vars for your one module only via:
+**Note:** If you want to test if your new module builds correctly, you can generate Dockerfiles which only contain this one module and all others removed. This allows for much faster Docker builds and you don't have to wait for all other modules to be built. To do so, generate only group_vars for your one module via:
 
 ```bash
 # Commands shown here are executed from root of this repository
@@ -42,14 +44,14 @@ make gen-dockerfiles
 
 ## Extension definition: `build.yml`
 
-See **[PHP-EXT-build.yml.md](../doc/PHP-EXT-build.yml.md)** how to alter the `build.yml` file.
+See **[PHP-EXT-build.yml.md](../doc/contributor/PHP-EXT-build.yml.md)** how to alter the `build.yml` file.
 
 
 ## Extension definition: `options.yml`
 
-See **[PHP-EXT-options.yml.md](../doc/PHP-EXT-options.yml.md)** how to alter the `options.yml` file.
+See **[PHP-EXT-options.yml.md](../doc/contributor/PHP-EXT-options.yml.md)** how to alter the `options.yml` file.
 
 
 ## Extension definition: `test.yml`
 
-See **[PHP-EXT-test.yml.md](../doc/PHP-EXT-test.yml.md)** how to alter the `test.yml` file.
+See **[PHP-EXT-test.yml.md](../doc/contributor/PHP-EXT-test.yml.md)** how to alter the `test.yml` file.