Update test documentation with GitHub secrets

Document the accounts and repo-specific domain names required to run the dynamic DNS tests.

Also document the GitHub "secrets" that must be stored for CI testing to work.

test/README-Testing.md

@@ -10,6 +10,23 @@ For continuous integration testing we have the following:
 2. Then runs the `bats` test scripts (all the files with a ".bats" extension) for each OS (alpine, centos6, debian, ubuntu)
 3. Runs the `bats` test script against the staging server (using ubuntu docker image and duckdns.org)
 
+Tests can also be triggered manually from the GitHub website.
+
+For dynamic DNS tests, you need accounts on duckdns.org and dynu.com, and need to create 4 domain names in each account.
+
+For duckdns.org:
+- Add DUCKDNS_TOKEN to your repository's environment secrets.  The value is your account's token
+- Add domains <reponame>-centos7-getssl.duckdns.org, wild-<reponame>-centos7.duckdns.org, <reponame>-ubuntu-getssl.duckdns.org, and wild-<reponame>-ubuntu-getssl.duckdns.org
+
+For dynu.com:
+ - Add DYNU_API_KEY to your repository's environment secrets.  The value is your account's API Key.
+ - Add domains <reponame>-centos7-getssl.freedns.org, wild-<reponame>-centos7.freedns.org, <reponame>-ubuntu-getssl.freedns.org, and wild-<reponame>-ubuntu-getssl.freedns.org
+
+To run dynamic DNS tests outside the CI environment, you need accounts without <reponame> in the domain names.  Export the environment variable corresponding to the secrets (with the same values).
+
+For individual accounts, <reponame> is your github account name.
+
+
 ## To run all the tests on a single OS
 
 1. Start `pebble` and `challtestsrv` using ```docker-compose up -d --build```