[Keymap] Update bface p3lim keymap (#13582)

keyboards/winkeyless/bface/keymaps/p3lim/README.md

@@ -2,13 +2,20 @@
 
 ![](https://user-images.githubusercontent.com/26496/61170794-bf8a2c80-a56e-11e9-893f-f1766e7a9a04.png)
 
-My layout using the winkeyless b.face X2 PCB. The keys indicated with a gray color was not supported by the layout so a custom one was made.
+My layout using the winkeyless b.face X2 PCB.
 
 ### Building & Flashing
 
-- Hold <kbd>LCTRL</kbd> while connecting to put in flashing mode
-- Follow instructions in the main _bface_ directory
+- Set up QMK
+	- `pip install --user qmk`
+	- `qmk setup`
+- Add udev rules if on Linux
+	- Follow the docs: <https://docs.qmk.fm/#/faq_build?id=linux-udev-rules>
+- Build and flash
+	- `qmk flash -kb winkeyless/bface -km p3lim`
+- Hold bottom-left key while connecting to put in flashing mode
 
 ### Layout notes
 
+The keys indicated with a gray color in the image above was not supported by the layout so a custom matrix was made.
 The two additional keys were on pins 22+41 and 22+42, C3+B1 and C3+B2, which is mapped to col 10 row 1 and col 10 row 2 in the matrix.