docs: add architecture and technical documentation

Description

add architecture and technical documentation

To give a general overview of techniques and decisions that were made in the implementation

Refs: #17

[x] I have followed the contributing guidelines
[x] I have performed IP checks for added or updated 3rd party libraries
[x] I have created and linked IP issues or requested their creation by a committer
[x] I have performed a self-review of my own code
[x] I have successfully tested my changes locally
[x] I have added tests that prove my changes work
[x] I have checked that new and existing tests pass locally with my changes
[x] I have commented my code, particularly in hard-to-understand areas
[x] I have added copyright and license headers, footers (for .md files) or files (for images)