📚👌 Improve readme

[s-weigand]

Just some minor improvements for users to find information quicker (preview of the updated readme).

Change summary

• 📚👌 Add badges
• 📚👌 Add conda install instruction
• 👌📚 Added LGTM and black badge

Checklist

• ✔️ Passing the tests (mandatory for all PR's)
• 📚 Adds documentation of the feature

[github-actions]

👈 Launch a binder notebook on branch s-weigand/pyglotaran-extras/update-readme

[s-weigand]

For the CI to pass this first needs #68

[codecov]

Codecov Report

Merging #69 (ee8c7df) into main (816cdab) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #69   +/-   ##
=======================================
  Coverage   40.85%   40.85%           
=======================================
  Files          22       22           
  Lines         629      629           
  Branches       90       90           
=======================================
  Hits          257      257           
  Misses        372      372           

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