Changes:
- Add an optional `bump` field to the crates in a prdoc.
- Explain the cargo semver interpretation for <1 versions in the release
doc.

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Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

Writing down the processes to do our releases.

Status: please review & approve so we can go ahead.

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Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com>
Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>
Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
Co-authored-by: Jegor Sidorenko <5252494+jsidorenko@users.noreply.github.com>