[AIRFLOW-XXX] Add How-To-Guide to GoogleCloudStorageToSFTPOperator

[TobKed]

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[codecov-io]

Codecov Report

Merging #6488 into master will decrease coverage by 0.24%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #6488      +/-   ##
==========================================
- Coverage   83.96%   83.72%   -0.25%     
==========================================
  Files         635      635              
  Lines       36661    36674      +13     
==========================================
- Hits        30783    30705      -78     
- Misses       5878     5969      +91

Impacted Files	Coverage Δ
airflow/operators/gcs_to_sftp.py	100% <ø> (ø)	⬆️
airflow/example_dags/example_gcs_to_sftp.py	100% <ø> (ø)	⬆️
airflow/kubernetes/volume_mount.py	44.44% <0%> (-55.56%)	⬇️
airflow/kubernetes/volume.py	52.94% <0%> (-47.06%)	⬇️
airflow/kubernetes/pod_launcher.py	45.25% <0%> (-46.72%)	⬇️
airflow/kubernetes/kube_client.py	33.33% <0%> (-41.67%)	⬇️
...rflow/contrib/operators/kubernetes_pod_operator.py	70.14% <0%> (-28.36%)	⬇️
airflow/hooks/postgres_hook.py	94.28% <0%> (-2.21%)	⬇️
airflow/utils/dag_processing.py	58.48% <0%> (+0.16%)	⬆️
airflow/hooks/dbapi_hook.py	91.52% <0%> (+0.84%)	⬆️
... and 1 more

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[TobKed]

Hey @mschickensoup, could you take a look in spare time please? CC @mik-laj

[turbaszek]

LGTM, just two suggestions ✅

[TobKed]

@mik-laj @nuclearpinguin I've applied your suggestions