Update the readme to describe documentation generation

Author: cmnrd

.github/workflows/github-pages.yaml

@@ -14,7 +14,7 @@ jobs:
         run: sudo apt-get install doxygen
 
       - name: Install sphinx and plugins
-        run: sudo pip3 install sphinx breathe exhale sphinx-rtd-theme
+        run: sudo pip3 install -r doc/requirements.txt
 
       - name: run doxygen
         run: doxygen reactor-cpp.doxyfile

README.md

@@ -31,6 +31,46 @@ make examples
 
 reactor-cpp can be build with [tracing support](https://github.com/tud-ccc/reactor-cpp/tree/master/tracing). This provides a powerful tool for analyzing and debugging reactor applications.
 
+## Documentaion
+
+A live version of the latest commit on master is automatically deployed and
+available [online](https://tud-ccc.github.io/reactor-cpp/index.html). For tests
+and other purposes, you can also build the documentation locally.
+
+First doxygen needs to be installed. On Ubuntu or Debian, run:
+```sh
+sudo apt-get install doxygen
+```
+
+Further we need several python packages. Assuming that both python3 and pip3
+are set up, run
+```sh
+pip3 --user install -r doc/requirements.txt
+```
+If python3 is the default on your system, run:
+```sh
+pip --user install -r doc/requirements.txt
+```
+
+Now we can run doxygen:
+```sh
+cd doc
+doxygen reactor-cpp.doxyfile
+```
+
+This already produces a decent html documentation in
+`doc/doxygen/html`. However, we want to use some of the features that sphinx
+provides and benefit from the more modern look and feel.
+
+Running
+```
+make html
+```
+in the `doc` directory will generate the sphinx based project documentaion in
+`doc/build/html`. Note that doxygen needs to be run first in order for this
+step to work properly.
+
+
 ## Publications
 
 * **DATE'20:** Christian Menard, Andrés Goens, Marten Lohstroh, Jeronimo Castrillon, [Achieving Determinism in Adaptive AUTOSAR](https://arxiv.org/pdf/1912.01367), Proceedings of the 2020 Design, Automation and Test in Europe Conference (DATE), EDA Consortium, Mar 2020.

doc/requirements.txt

@@ -0,0 +1,4 @@
+sphinx
+breathe
+exhale
+sphinx-rtd-theme

doc/source/.gitignore

@@ -0,0 +1 @@
+api