[Keyboard] Add PHDesign PH60/Multi Keyboard PCB (#25086)

* Add PH60/Multi Support

* Add PCB PIcture for README

* Remove MO(_FN2)

* README Typo Fix

* Layout and README Adjustment

* Add README for PHDesign Main Folder

* Keymap Improvement

* Update README.md

keyboards/phdesign/ph60/multi/readme.md

@@ -0,0 +1,28 @@
+# phdesign/ph60/multi
+
+![PromoImage](https://i.imgur.com/sUwC9mk.jpg)
+
+A 60% multi-layout supported keyboard PCB with open source keyboard case.
+
+* Keyboard Maintainer: [Team PHDesign](https://github.com/ph-design)
+* Hardware Supported: PH60/Multi PCB
+* Hardware Availability: 
+  - Store: https://e.tb.cn/h.6VMjUgWZkUGwq26?tk=oVyAeD6uPS2
+  - GitHub Repo: https://github.com/ph-design/PH60/tree/Rev.2/PCB_Rev2/Multi
+
+Make example for this keyboard (after setting up your build environment):
+
+    make phdesign/ph60/multi:default
+
+Flashing example for this keyboard:
+
+    make phdesign/ph60/multi:default:flash
+
+See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).
+
+## Bootloader
+
+Enter the bootloader in 3 ways:
+
+* **Bootmagic reset**: Hold down the key at (0,0) in the matrix (usually the top left key or Escape) and plug in the keyboard
+* **Physical reset button**: Briefly press the button on the back of the PCB - some may have pads you must short instead