adding new keyboard atset/atr1

[anubhavd7]

Description

Types of Changes

• [x ] Core
• Bugfix
• [x ] New feature
• Enhancement/optimization
• [x ] Keyboard (addition or update)
• [ x] Keymap/layout (addition or update)
• [ x] Documentation

Issues Fixed or Closed by This PR

Checklist

• [x ] My code follows the code style of this project: C, Python
• [ x] I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• [x ] I have updated the documentation accordingly.
• [x ] I have read the CONTRIBUTING document.
• [x ] I have added tests to cover my changes.
• [x ] I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[waffle87]

Please provide a link to where this keyboard can be purchased under the Hardware Availability section.

Suggested change

	* Hardware Supported:
	* ATR1 R1 *(ft. STM32F103)*
	* Hardware Availability:
	* Hardware Supported: ATR1 R1 PCB with STM32F103
	* Hardware Availability:

[waffle87]

There are still outstanding suggestions. Please do not mark things as resolved without acknowledging them. This has been an issue on your previous PR's as well.

[waffle87]

Please provide a link to where this keyboard can be purchased under the Hardware Availability section.