[Keyboard] Move Hillside out of handwired (#18751)

Co-authored-by: mmccoyd <mmccoyd@cs.berkley.edu>

keyboards/hillside/52/keymaps/default_dot_c/readme.md

@@ -0,0 +1,25 @@
+# Default Hillside 52 Layout (in .c format)
+
+This layout is for those who prefer defining their layout in a keymap.c,
+  instead of graphically with a keymap.json.
+It is the same as the [default keymap.json layout](https://github.com/qmk/qmk_firmware/blob/master/keyboards/hillside/52/keymaps/default),
+  except for having only a QWERTY base layer.
+  
+The make and flash commands are
+
+```
+make hillside/52:default_dot_c
+make hillside/52:default_doc_c:flash
+
+```
+
+It also serves as a simple, clean layout 
+  to verify that the configuration and switches work.
+Use the [QMK Configurator Tester](https://config.qmk.fm/#/test) 
+ to see that the switches produce output.
+All the keys should register on the layout tester 
+  except for the caps word and the two layer keys.
+The LEDs should glow a nice red.
+If they do not, you may need to clear the persistent EEPROM settings with the
+  EE_CLR key on the adjust layer,
+  or enable them with the RGB_TOG key.