Add a README.

README.rst

@@ -0,0 +1,28 @@
+wrmath
+======
+
+The WNTRMUTE ROBOTICS maths library is a C++11 library containing various
+useful maths components for robotics and navigation.
+
+Dependencies
+------------
+
+This project uses Google Test as a dependency::
+
+  $ git submodule update --init --recursive
+
+Additionally, building this requires
+
++ a C++11 compiler
++ CMake (minimum 3.15 to support code coverage, otherwise 3.10).
++ Doxygen
+
+
+Building
+--------
+
+.. code::
+
+    mkdir build
+    cmake ..
+    make check