feat: bash completion and command docs automation

[tuunit]

📝 Summary

This PR introduces bash completion for kubara:

# add the following line to your .bashrc
$ source <(kubara completion bash)
# or for zsh
$ source <(kubara completion zsh)
# after loading your rc file or opening a new terminal you will have tab completion for kubara
$ kubara <tab>
bootstrap  -- Bootstrap ArgoCD onto the specified cluster with optional external-secrets and prometheus CRD
generate   -- generates files from embedded templates and the config file; by default for both Helm and Terraform
help       -- Shows a list of commands or help for one command
init       -- Initialize a new kubara directory
schema     -- Generate JSON schema file for config structure

🧩 Type of change

• 🔧 CLI / Go code
• 📦 Helm chart
• 🧱 Terraform module
• 📝 Documentation
• 🧪 Test or CI change
• ♻️ Refactor / cleanup

⚠️ Is this a breaking change?

• Yes, this change breaks existing functionality (explain in summary)

🧪 Testing

• CI passed
• Manually tested (local/dev cluster)
• Unit tested
• Not tested (explain why below)

🔗 Related Issues / Tickets

✅ Checklist

• Code compiles and passes all tests
• Linting and style checks pass
• Comments added for complex logic
• Documentation updated (if applicable)

📎 Additional Context (optional)

[tuunit]

urfave/cli-docs#22

[fabian-schmitt]

lgtm 👍🏽