docs: update quay docs for auth (#10612)

(cherry picked from commit 99d2d2b)

docs/developers/PACKAGING.md

@@ -6,13 +6,29 @@ The packaging steps require certain tools to be setup before hand to work. These
 
 ## Go Version
 
-Telegraf will be built using the latest version of Go whenever possible. Incrementing the version is maintained by the core Telegraf team because it requires access to an internal docker repository that hosts the docker CI images. When a new version is released, the following process is followed:
+Telegraf will be built using the latest version of Go whenever possible.
+
+### Update CI image
+
+Incrementing the version is maintained by the core Telegraf team because it requires access to an internal docker repository that hosts the docker CI images. When a new version is released, the following process is followed:
 
 1. Within the `Makefile` and `.circleci\config.yml` update the Go versions to the new version number
 2. Run `make ci-<latest version>` where `<latest version>` refers to the new Go version number (this requires internal permissions)
 3. The files `scripts\installgo_mac.sh` and `scripts\installgo_windows.sh` need to be updated as well with the new Go version and SHA
 4. Create a pull request with these new changes, and verify the CI passes and uses the new docker image
 
+See the [previous PRs](https://github.com/influxdata/telegraf/search?q=chore+update+go&type=commits) as examples.
+
+### Access to quay.io
+
+A member of the team needs to invite you to the quay.io organization.
+To push new images, the user needs to do the following:
+
+1. Create a password if the user logged in using Google authentication
+2. Download an encrypted username/password from the quay.io user page
+3. Run `docker login quay.io` and enter in the encrypted username and password
+  from the previous step
+
 ## Package using Docker
 
 This packaging method uses the CI images, and is very similar to how the