Update README.md

Release v0.1.1

Fix `-` modifier (#20)

Use keyword() for options

Use SPDX license identifier

Update mix.exs

Remove single pipe

Update version requirement recommendation

Fix README code snippets

Simplify docs

Drop default padding for %u, closes #18

Highlight README.md code with Elixir syntax colors (#17)

Add link to online documentation on README.md

add hex package data

Merge pull request #16 from plataformatec/gsf-redo-abbreviation-options