feat: testing commands in CLI docs

[benesjan]

Fixes #1893

Note: It replaces the incorrect private key value in docs. The problematic command was:

aztec-cli create-account --private-key 0x6622c828e9cd5adc86f10878765fe921d2b8cb2c79bdbc391157e43811ce88e3

This could bite users so we should ideally merge this before next release.

Checklist:

Remove the checklist to signal you've completed it. Enable auto-merge if the PR is ready to merge.

• If the pull request requires a cryptography review (e.g. cryptographic algorithm implementations) I have added the 'crypto' tag.
• I have reviewed my diff in github, line by line and removed unexpected formatting changes, testing logs, or commented-out code.
• Every change is related to the PR description.
• I have linked this pull request to relevant issues (if any exist).