update test suite docs

[smoors]

updates to match the changes made in the test suite

• hpctestlib is no longer required
• replace example configuration file with link to the example in the test suite repo
• update configuration file docs
• replace release notes with release notes in the test suite repo
• usage: add prerequisites section
• usage: add filtering by environment
• usage: add --list -C option

not included: update to the tutorial on writing portable tests. can be done in a later PR.