Docs Update: Correct Storage Quota Documentation

[wshahn]

What steps does it take to reproduce the issue?
When setting a quota on a collection (https://guides.dataverse.org/en/latest/api/native-api.html#id2), the docs instruct the usage of PUT. This doesn't work, but POST does work.

• When does this issue occur?
  When using PUT to set a storage quota, following the documentation.

• Which page(s) does it occurs on?
  API only.

• What happens?
  Error returned when using PUT to set a storage quota:

$ curl -X PUT -H "X-Dataverse-key:$API_TOKEN" "$SERVER_URL/api/dataverses/$ID/storage/quota/$SIZE_IN_BYTES"
{"status":"ERROR","code":405,"message":"API endpoint does not support this method. Consult our API guide at http://guides.dataverse.org.","requestUrl":"http://localhost:8080/api/v1/dataverses/root/storage/quota/<size goes here>","requestMethod":"PUT"}

• To whom does it occur (all users, curators, superusers)?
  For superusers.

• What did you expect to happen?
  I expected the storage quota to be set following the documentation.

Which version of Dataverse are you using?
v6.5

Any related open or closed issues to this bug report?
No.

Screenshots:
None.

Are you thinking about creating a pull request for this issue?
Yes.