README: add basic info

README.md

@@ -1,2 +1,14 @@
 # hyprutils
-Hyprland utilities library used across the ecosystem
+
+Hyprutils is a small C++ library for utilities used across the Hypr* ecosystem.
+
+## Stability
+
+Hyprutils depends on the ABI stability of the stdlib implementation of your compiler. Sover bumps will be done only for hyprutils ABI breaks, not stdlib.
+
+## Building
+
+```sh
+cmake --no-warn-unused-cli -DCMAKE_BUILD_TYPE:STRING=Release -DCMAKE_INSTALL_PREFIX:PATH=/usr -S . -B ./build
+cmake --build ./build --config Release --target all -j`nproc 2>/dev/null || getconf _NPROCESSORS_CONF`
+```