Format markdown

[ralfhandl]

Fixes #48

• [x] scripts/format-markdown.sh: bash script to reformat source(s)
• [x] package.json
  • [x] add dependencies
  • [x] add npm script format-markdown
• [x] package-lock.json: check in to fix dependencies
• [x] .markdownlint.yaml: added
• [x] versions/1.0.0.md: use respec-style normative references
• [x] build.sh: remove tweak code for normative references

Part of

• 53

Partially conflicts with

• 47

[lornajane]

Looks good, but can you update now that #46 is merged so we can see which changes are here?

[ralfhandl]

Updated from main, now contains only formatting-related changes.