add docs readme

docs/README.md

+# Doxygen instructions
+
+**A quick run down of using doxygen**
+
+## Intro
+
+Basically Doxygen is going to look at every `.cpp` and `.h` file and look out for specifically formatted comments.
+
+The full documentation can be [found here](http://www.doxygen.nl/manual/docblocks.html), but here is enough to get started. A Doxyfile has already been generated and options can be tweaked as necessary.
+
+### install
+
+#### Windows
+
+You can install the binary [following these instruction](http://www.doxygen.nl/manual/install.html#install_bin_windows)
+
+#### macOS
+
+```
+brew install doxygen
+```
+
+#### Linux Ubuntu / Debian
+
+```
+sudo apt-get install doxygen
+```
+
+### Comment blocks
+
+Comment blocks can take a number of forms but I suggest using Javadoc c-style comments
+
+> ... starting with two \*'s, like this:
+>
+> ```cpp
+> /**
+> * ... text ...
+> */
+> ```
+
+
+#### Commands
+
+Commands basically allow for comments to broken down into sections. They can start with either `\` or `@`.
+There are a ton of different commands, though all the is needed is just a `\brief` tag at most. [A full reference can be found here](http://www.doxygen.nl/manual/commands.html). You don't need to be beholden to these commands, [you can use your own custom commands if you like](http://www.doxygen.nl/manual/custcmd.html).
+
+A boiler plate commented file would look something like
+
+```cpp
+/** \file filename.h
+    \brief A Documented file.
+
+    filename.h MUST be the same name as the actual file
+*/
+
+/** \class Test
+    \brief A test class.
+
+    A more detailed class description.
+*/
+class Test{};
+
+/**
+  \fn void example(int arg1);
+  \brief an example function
+  \param arg1 the first argument
+ */
+void example(int arg1);
+```
+
+The `doxygen_test.h` is provided as an example.
+
+
+### Running Doxygen
+
+run in the command line as
+
+```sh
+cd path/to/repo/
+doxygen Doxyfile
+```