RHIDP-2862: Add air-gapped use case to TechDocs plugin doc (#1249)

* Added note about air-gapped

* Incorporated Tomas's comment

Author: pabel-rh

modules/customizing-techdocs/proc-techdocs-using-odf-storage.adoc

@@ -4,7 +4,12 @@
 
 You can configure {odf-name} to store the files that TechDocs generates instead of relying on other cloud storage solutions.
 
-{odf-name} provides an `ObjectBucketClaim` custom resource (CR) that you can use to request an S3 compatible bucket backend. You must install the {odf-name} Operator to use this feature.
+{odf-name} provides an `ObjectBucketClaim` custom resource (CR) that you can use to request an S3-compatible bucket backend. You must install the {odf-name} Operator to use this feature.
++
+[NOTE]
+====
+For air-gapped environments, using {odf-name} is the recommended storage for TechDocs. 
+====
 
 .Prerequisites