feat: bump version to v0.5.0

fix: send to kindle may reject emails without a body

feat: check ebook size before sending and show warning

chore: bump version to v0.3.0

- Reduce default article count from 100 to 15 in order to reduce
  processing time and output file size (by @zsoltika)
- Add new option for search-string specifier which can also be used to
  change the article fetch order to oldest article first from the
  current default of newest article first (by @zsoltika)

New Contributors:
- @zsoltika

docs: improve usage instructions and document configuration options

feat: switch to new endpoint for fetching list of articles

The 'articles' endpoint has been removed in Omnivore GraphQL API.
Therefore we are now using 'search' endpoint to fetch list of articles

fixes #1

feat: initial commit