nostr : book: add event_id python examples

- Added event ID examples (construct/format/parse/access/verify)

- Corrected minor typo in `04_04-tag.md`

Closes https://github.com/rust-nostr/nostr/pull/493

Signed-off-by: Yuki Kishimoto

https://github.com/rust-nostr/nostr/commit/cb6e5cca4fe8bcbc7b56d356417684c5e8336fcf