Octagon V2 Refactor (#2170)

* rename octagon_v2 directory to octagon directory

* Move octagon_v2 files to v2 sub-directory

* Edit readme files

* setup header files for building multiple versions of the Duck
Octagon.

* Changes as per Jack's PR 2170 comments

keyboards/octagon/keymaps/default/keymap.c

@@ -13,7 +13,7 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-#include "octagon_v2.h"
+#include "octagon.h"
 
 const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
     /* layer 0: qwerty */

keyboards/octagon/octagon.c

@@ -0,0 +1 @@
+#include "octagon.h"

keyboards/octagon/octagon.h

@@ -0,0 +1,10 @@
+#ifndef OCTAGON_H
+#define OCTAGON_H
+
+#include "quantum.h"
+
+#ifdef KEYBOARD_octagon_v2
+    #include "v2.h"
+#endif
+
+#endif

keyboards/octagon/readme.md

@@ -0,0 +1,9 @@
+# Duck Octagon
+
+Non official firmware for custom Korean keyboard with 75% key layout made by Duck.
+
+See [build environment setup](https://docs.qmk.fm/build_environment_setup.html) then the [make instructions](https://docs.qmk.fm/make_instructions.html) for more information.
+
+Make example for this keyboard (after setting up your build environment):
+
+    make octagon/v2:default

keyboards/octagon/rules.mk

@@ -0,0 +1 @@
+DEFAULT_FOLDER = octagon/v2

keyboards/octagon/v2/readme.md

@@ -9,7 +9,7 @@ Hardware Availability: Wait until GB of the next revision
 
 Make example for this keyboard (after setting up your build environment):
 
-    make octagon_v2:default
+    make octagon/v2:default
 
 See [build environment setup](https://docs.qmk.fm/build_environment_setup.html) then the [make instructions](https://docs.qmk.fm/make_instructions.html) for more information.
 
@@ -25,4 +25,4 @@ The Duck Octagon V2 PCB consists of:
 ## Notes
 Thanks to Ralf Schmitt for previous implementations in his [TMK fork](https://github.com/xauser/tmk_keyboard/tree/xauser/) and few helping words.
 
-Based heavily on Rasmus Schults [Duck Lightsaver QMK Port](https://github.com/qmk/qmk_firmware/tree/master/keyboards/lightsaver)
+Based heavily on Rasmus Schults [Duck Lightsaver QMK Port](https://github.com/qmk/qmk_firmware/tree/master/keyboards/lightsaver)

keyboards/octagon/v2/v2.c

@@ -13,7 +13,7 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-#include "octagon_v2.h"
+#include "v2.h"
 #include "indicator_leds.h"
 
 enum BACKLIGHT_AREAS {

keyboards/octagon/v2/v2.h

@@ -13,10 +13,10 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-#ifndef OCTAGON_V2_H
-#define OCTAGON_V2_H
+#ifndef V2_H
+#define V2_H
 
-#include "quantum.h"
+#include "../octagon.h"
 
 #define KEYMAP( \
     K5A, K5B, K5C, K5D, K5E, K5F, K5G, K5H, K5I, K5J, K5K, K5L, K5M, K5N, K5O,     K5Q, \