Update readme

[crangelsmith]

Updates to README

• [x] Adapt introduction from JOSS paper intro from @JasonGellis
• [x] Add TOC
• [x] New section structure
• [x] Add team section
• [x] Github contribution guidelines
• [x] Making clear which sections are missing (with WIP emoji)
• [x] Aesthetics (emojis, etc).
• [x] Removing the old licence

This PR should be merged after PR #110

Things to finish before merging:

• [x] @JasonGellis to take a look at the new structure and comment
• [x] @crangelsmith to add output images and data (after having the scale for the test image)
• [x] Add workflow diagram (@JasonGellis working on this for the JOSS paper)
• [ ] Write some small guidelines of expected drawing style for pylithics (@JasonGellis and @Rob-LCHES)
• [x] @crangelsmith to fix broken links
• [x] @JasonGellis and @Rob-LCHES OrchID for citation
• [x] Adding example dataset

I think after merging this PR the repo should be opened 😀

[crangelsmith]

Most of the missing parts are finished, except for #112 which is now its own issue. This PR is ready to merge and the repo to be opened.