Add docker configuration for gd library (#816)

Co-authored-by: pcescon <pcescon@degetel.com>

bundles/media/imagine-adapter.rst

@@ -15,6 +15,20 @@ GD
 
 The simplest adapter is GD and it has no external dependencies besides the PHP extension.
 
+**Docker:**
+
+To use the GD extension, you need to install it with docker-php-ext-install. However, GD requires Linux libraries to function properly. Depending on the type of file you want to generate (such as JPG, PNG, or WebP), you also need to install the corresponding libraries.
+..code-block:: bash
+
+    RUN apt-get update && apt-get install -y \
+        libfreetype6-dev \
+        libwebp-dev \
+        libjpeg62-turbo-dev \
+        libpng-dev \
+        && docker-php-ext-configure gd --with-freetype --with-jpeg --with-webp \
+        && docker-php-ext-install -j$(nproc) gd \
+
+
 Imagick
 -------