Initial work on basic documentation.

docs/docs/dev-posix-board.md

@@ -0,0 +1,26 @@
+---
+id: dev-posix-board
+title: Native Posix board target
+---
+
+In order to iterate quickly on firmware features, it can
+be helpful to build and run the firmware on your local
+workstation, with generated virtual press/release events
+flowing into the handler functions.
+
+To do this, you can build ZMK targetting the
+`native_posix` board.
+
+```
+west build --pristine --board native_posix
+```
+
+Once built, you can run the firmware locally:
+
+```
+./build/zephyr/zephyr.exe
+```
+
+## Virtual Key Events
+
+The virtual key presses are hardcoded in `boards/native_posix.overlay` file. should you want to change the sequence to test various actions like Mod-Tap, etc.