Tada68 Fixes and Minor Refactoring (#7820)

* fix ANSI layout macro reference

* update ISO layout macro and enable 65_iso community layout support

- rename to LAYOUT_65_iso (with LAYOUT_iso alias for backwards compatibility)
- rename position k2c to k1d (electrical position)

* rules.mk templating

* tada68.h: use #pragma once include guard

* config.h: use #pragma once include guard

* make product id unique

* update info.json

* update readme

* cleanup default keymap

- keycode alignment
- layout macro reference
- four-space indent

* remove matrix_*_user functions from tada68.h

keyboards/tada68/readme.md

@@ -1,17 +1,16 @@
-TADA68
-======
+# TADA68
 
 A compact 65% keyboard.
 
-Keyboard Maintainer: QMK Community  
-Hardware Supported: TADA68 PCB  
-Hardware Availability: [kbdfans](https://kbdfans.myshopify.com/products/tada68-mechanical-keyboard-gateron-swtich-65-layout-dye-sub-keycaps-cherry-profils?variant=34710238797), [kbdist](http://www.kbdist.com/)
+* Keyboard Maintainer: QMK Community
+* Hardware Supported: TADA68 PCB
+* Hardware Availability: [kbdfans](https://kbdfans.myshopify.com/products/tada68-mechanical-keyboard-gateron-swtich-65-layout-dye-sub-keycaps-cherry-profils?variant=34710238797), [kbdist](http://www.kbdist.com/)
 
 Make example for this keyboard (after setting up your build environment):
 
     make tada68:default
 
-See [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) then the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information.
+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).
 
 ## Firmware Format