Add Helm repository cmd docs

docs/cmd/tk_bootstrap_github.md

docs/cmd/tk_bootstrap_gitlab.md

docs/cmd/tk_create_kustomization.md

docs/cmd/tk_create_source.md

docs/cmd/tk_create_source_git.md

docs/cmd/tk_create_source_helm.md

docs/cmd/tk_delete_kustomization.md

docs/cmd/tk_delete_source.md

docs/cmd/tk_delete_source_git.md

docs/cmd/tk_delete_source_helm.md

docs/cmd/tk_export_kustomization.md

docs/cmd/tk_export_source.md

docs/cmd/tk_export_source_git.md

docs/cmd/tk_export_source_helm.md

docs/cmd/tk_get.md

docs/cmd/tk_get_kustomizations.md

docs/cmd/tk_get_sources.md

docs/cmd/tk_get_sources_git.md

docs/cmd/tk_get_sources_helm.md

docs/cmd/tk_reconcile_source_helm.md