Update and finish documentation

[vojtechkral]

• [x] Update installation guide

  • [x] Explain built-in tectonic on Windows
  • [x] Link tectonic-less binary for Windows

• Licensing, credits, authors

  • [x] add contributors note
  • [x] fonts licensing
  • [x] Tvrz

• Project setup

  • [x] sans_font
  • [x] sorted ToC

• Writing / MD

  • [x] finalize
  • [x] bare chords
  • [x] smart_punctuation

• [x] Notation & Transposition

• [x] Fonts

• [x] Images

  • [x] DPI

• [x] TeX - BARD_TEX, Settings::tex, Output::tex_runs

  • [x] link from code

• [x] Templates

  • [x] Upgrading
  • [x] "HTML" extensions

• [x] JSON & XML

• [x] Script

• [x] Hovorka

• [x] bard.toml reference

• [x] migration guide to v2

  • [x] link from code

• [x] Review / re-read the whole thing

• [x] Refactor README.md

• [x] Remove old doc