doc: + README.md

README.md

@@ -1 +1,38 @@
-# xo-unit
+# unit library
+
+Provides compile-time dimension checking and scaling.
+
+Similar to `boost::units`,  but:
+1. streamlined: assumes modern (c++20) support
+2. supports fractional dimensions (rational powers)
+
+## Getting Started
+
+### build + install dependencies
+
+- [github/Rconybea/reflect](https://github.com/Rconybea/reflect)
+
+### build + install
+```
+$ cd xo-unit
+$ mkdir .build
+$ cd .build
+$ PREFIX=/usr/local  # or wherever you prefer
+$ cmake -DCMAKE_MODULE_PATH=${PREFIX}/share/cmake -DCMAKE_PREFIX_PATH=${PREFIX} -DCMAKE_INSTALL_PREFIX=${PREFIX} ..
+$ make
+$ make install
+```
+
+### build for unit test coverage
+```
+$ cd xo-unit
+$ mkdir .build-ccov
+$ cd .build-ccov
+$ cmake -DCMAKE_MODULE_PATH=${INSTALL_PREFIX}/share/cmake  -DCMAKE_PREFIX_PATH=${INSTALL_PREFIX} -DCODE_COVERAGE=ON -DCMAKE_BUILD_TYPE=Debug ..
+```
+
+### LSP support
+```
+$ cd xo-unit
+$ ln -s .build/compile_commands.json  # lsp will look for compile_commands.json in the root of the source tree
+```