[2.9.0] #1151 Add documentation for OCI feature in Apps & Marketplace Section (#1171)

* 1151 Add documentation for OCI feature in Apps & Marketplace Section

* rename file, edit intro, add canonical link

* edited refresh instructions

* edited update instructions

* edited delete instructions

* initial attempt at add an oci registry

* completed edit of first section, made misc revisions to other text

* escape angle brackets

* moved file

* added edited text of helm-charts-in-rancher from #1320

* instructions updated to sync with #1320

* updated with suggestions from review

* more edits

* more suggestions from reviews

* most changes addressed except line 101

* line 101 rate limiting addressed

* Apply suggestions from code review

Co-authored-by: Diogo Souza <diogo.souza@suse.com>
Co-authored-by: Sakala Venkata Krishna Rohit <rohitsakala@gmail.com>

* Apply suggestions from code review

Co-authored-by: Diogo Souza <diogo.souza@suse.com>

* Apply suggestions from code review

Co-authored-by: Sakala Venkata Krishna Rohit <rohitsakala@gmail.com>

* rename

* clarified what triggers the exp backoff

* edit suggestions on clarifications

* Apply suggestions from code review

Co-authored-by: Sunil Singh <sunil.singh@suse.com>

* Apply suggestions from code review

Co-authored-by: Sunil Singh <sunil.singh@suse.com>

* sidebar for v2.9

* experimental feature caution

* ported to docs/

* removed slashes as they were displaying

* using literals to get around annoying confusion around how to treat slashes

* Apply suggestions from code review

Co-authored-by: Billy Tat <btat@suse.com>

* revised caution box

* drop the yet

* rm'd 2 instances of 'rate-limiting'

* added link to limitations section

* rm'd bit that begs the question about other options

* Apply suggestions from code review

Co-authored-by: Billy Tat <btat@suse.com>

* Apply suggestions from code review

Co-authored-by: Sunil Singh <sunil.singh@suse.com>

---------

Co-authored-by: Diogo Souza <diogo.souza@suse.com>
Co-authored-by: Sakala Venkata Krishna Rohit <rohitsakala@gmail.com>
Co-authored-by: Sunil Singh <sunil.singh@suse.com>
Co-authored-by: Billy Tat <btat@suse.com>

versioned_sidebars/version-2.9-sidebars.json

@@ -596,7 +596,8 @@
                 "id": "how-to-guides/new-user-guides/helm-charts-in-rancher/helm-charts-in-rancher"
               },
               "items": [
-                "how-to-guides/new-user-guides/helm-charts-in-rancher/create-apps"
+                "how-to-guides/new-user-guides/helm-charts-in-rancher/create-apps",
+                "how-to-guides/new-user-guides/helm-charts-in-rancher/oci-repositories"
               ]
             },
             {