docs: fix optional arguments shown as required, document defaults and dry-run

[jirkasemmler]

Changes:

Second half of the README audit - the presentational findings. Nothing here is a false statement; each one just makes a reader do more work than needed.

• Optional arguments shown as required. Three usage lines put optional args in <angle brackets>: hostname-suffix in manage:reset-organization-workspace-passwords and manage:set-organization-storage-backend, and hostname-suffix, reason, estimatedEndTime in manage:set-organization-maintenance-mode. Now [<bracketed>].
• Undocumented defaults. hostname-suffix = keboola.com for both BYODB commands, and connectionUrl = https://connection.keboola.com for storage:lineage-events-export. Both BYODB sections now list arguments and options in the same format the rest of the README uses.
• Five sections did not mention dry-run even though the code prints DRY RUN without --force: the two BYODB commands above, plus manage:projects-add-feature, manage:projects-remove-feature and manage:organizations-add-feature. Verified in each command before documenting it. Reuses the exact sentence the neighbouring add-feature-to-templates section already had, rather than inventing new phrasing.
• Fixes Hostname sUffix.

Stacked on #120 - both PRs edit README.md, so this branch is based on that one to avoid a guaranteed conflict. Merge #120 first; the diff shown here against main will then be just this commit. The diff against #120's branch is 29 insertions / 4 deletions.

After both, re-running the audit script reports 0 problems: every registered command has its own section, every default is documented, no optional argument is presented as required, and every command with --force says so.

Docs only, no code touched.

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Additional notes

⚠️ Don't forget to release new version after merge

🤖 Generated with Claude Code

[jirkasemmler]

Superseded by #122 — same commit, rebased onto main.

This PR was auto-closed when #120 was merged with branch deletion: it was stacked on jirka/readme-safety-fixes, so deleting that branch removed its base and GitHub closed it rather than retargeting. A closed PR cannot have its base changed, hence the new one.