Keyboard: initial support for XD87 (#4182)

* Keyboard: initial support for XD87

* Add row/col pin configuration for XD87 PCB

* Add default ISO layout

* Fix incorrect KC in default_tkl_iso

The KC_NUBS is duplicated in the TKL ISO layout.
Compare with the fullsize ISO which has a KC_NUHS
in the corresponding place.

* Add support for community layouts

* Add TKL ANSI layout

* Enable TKL ISO/ANSI community layout

* Fix LAYOUT_all

* Configure backlighting for XD87

* Various documentation changes

keyboards/xd87/readme.md

@@ -0,0 +1,26 @@
+# XD87
+
+![XD87](https://i.imgur.com/qVyOies.jpg)
+
+
+- Keyboard Maintainer: [Alexander Fougner](https://github.com/fougner)  
+- Hardware Supported: XD87 PCB v1.1  
+- Hardware Availability:  
+	- [KPrepublic.com](https://kprepublic.com/products/xd87-xd87-xd80-custom-mechanical-keyboard-kit80-supports-tkg-tools-support-underglow-rgb-pcb-programmed-gh80-kle)
+	- [AliExpress](https://www.aliexpress.com/item/xd87-XD87-XD80-Custom-Mechanical-Keyboard-Kit80-Supports-TKG-TOOLS-Support-Underglow-RGB-PCB-programmed-gh80/32892540743.html)
+
+Make example for this keyboard (after setting up your build environment):
+
+    make xd87:default
+
+It also supports the tkl_ansi and tkl_iso community layouts:
+
+	  # Build firmware with ANSI layout
+	  make xd87:default_tkl_ansi
+	  # Build firmware with ISO layout
+	  make xd87:default_tkl_iso
+
+
+The keyboard can be reset to bootloader by using bootmagic (space+b by default) or short out the small connector between the Delete and End keys.
+
+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).