docs: Cairo dependency described in the MkDocs section

.gitpod/Dockerfile

@@ -2,7 +2,7 @@ FROM trainiteu/gitpod-cpp
 
 # Add clang apt repositories
 RUN lsb_rel=`lsb_release -cs` && \
-    sudo add-apt-repository "deb http://apt.llvm.org/${lsb_rel}/ llvm-toolchain-${lsb_rel}-16 main"
+  sudo add-apt-repository "deb http://apt.llvm.org/${lsb_rel}/ llvm-toolchain-${lsb_rel}-16 main"
 
 # Install older compilers supported by the project
 RUN sudo install-packages \
@@ -10,10 +10,4 @@ RUN sudo install-packages \
   clang-16
 
 # Install mkdocs dependencies
-RUN sudo install-packages \
-  libcairo2-dev \
-  libfreetype6-dev \
-  libffi-dev \
-  libjpeg-dev \
-  libpng-dev \
-  libz-dev
+RUN sudo install-packages

docs/getting_started/installation_and_usage.md

@@ -475,6 +475,10 @@ is with `pip`:
 pip install -U mkdocs-material mkdocs-rss-plugin
 ```
 
+Additionally, a [Cairo Graphics library](https://www.cairographics.org/) is required by
+Material for MkDocs. Please follow the
+[official MkDocs documentation to install it](https://squidfunk.github.io/mkdocs-material/plugins/requirements/image-processing/#cairo-graphics).
+
 After that, you can either:
 
 - easily [start a live server to preview the documentation as you write](https://squidfunk.github.io/mkdocs-material/creating-your-site/#previewing-as-you-write)