Create tech stack docs (techstack.yml and techstack.md)

[stack-file]

Adding tech stack documentation to allow anyone to easily see what is being used in this repo without digging through config files. Two files are being added: techstack.yml and techstack.md. techstack.yml contains data on all the technologies being used in this repo. techstack.md is a visualization of the YML file and displays the tech stack data in a pretty Markdown file.

💡 Protip: techstack.md contains a comment at the top of the file that the following README snippet (with and without the logos) at the top of the file as a comment:

<--- Readme.md Snippet without images Start --->

Tech Stack

IHTSDO/otf-common is built on the following main stack:

• Java – Languages
• Spring Data – Database Tools
• JUnit – Testing Frameworks
• Mockito – Testing Frameworks
• SLF4J – Log Management
• Dataform – Business Intelligence

Full tech stack here

<--- Readme.md Snippet without images End --->

Get the code:

## Tech Stack
IHTSDO/otf-common is built on the following main stack:

- [Java](https://www.java.com) – Languages
- [Spring Data](https://spring.io/projects/spring-data) – Database Tools
- [JUnit](http://junit.org/) – Testing Frameworks
- [Mockito](https://site.mockito.org/) – Testing Frameworks
- [SLF4J](http://slf4j.org/) – Log Management
- [Dataform](https://dataform.co/) – Business Intelligence

Full tech stack [here](/techstack.md)

---

<--- Readme.md Snippet with images Start --->

Tech Stack

IHTSDO/otf-common is built on the following main stack:

• Java – Languages
• Spring Data – Database Tools
• JUnit – Testing Frameworks
• Mockito – Testing Frameworks
• SLF4J – Log Management
• Dataform – Business Intelligence

Full tech stack here

<--- Readme.md Snippet with images End --->

Get the code:

## Tech Stack
IHTSDO/otf-common is built on the following main stack:

- <img width='25' height='25' src='https://img.stackshare.io/service/995/K85ZWV2F.png' alt='Java'/> [Java](https://www.java.com) – Languages
- <img width='25' height='25' src='https://img.stackshare.io/service/7624/IG6D4Ro2_400x400.png' alt='Spring Data'/> [Spring Data](https://spring.io/projects/spring-data) – Database Tools
- <img width='25' height='25' src='https://img.stackshare.io/service/2020/874086.png' alt='JUnit'/> [JUnit](http://junit.org/) – Testing Frameworks
- <img width='25' height='25' src='https://img.stackshare.io/service/2021/4y634TJm_400x400.jpg' alt='Mockito'/> [Mockito](https://site.mockito.org/) – Testing Frameworks
- <img width='25' height='25' src='https://img.stackshare.io/service/2805/05518ecaa42841e834421e9d6987b04f_400x400.png' alt='SLF4J'/> [SLF4J](http://slf4j.org/) – Log Management
- <img width='25' height='25' src='https://img.stackshare.io/service/11236/Group_22__3_.png' alt='Dataform'/> [Dataform](https://dataform.co/) – Business Intelligence

Full tech stack [here](/techstack.md)