Update QA docs

Use consistent language (end-to-end instead of integration).

Clarify purpose of `qa/specs/features/` vs. `spec`

doc/development/testing_guide/testing_levels.md

@@ -159,6 +159,10 @@ Every new feature should come with a [test plan].
 
 > See [end-to-end tests](end_to_end_tests.md) for more information.
 
+Note that `qa/spec` contains unit tests of the QA framework itself, not to be
+confused with the application's [unit tests](#unit-tests) or 
+[end-to-end tests](#black-box-tests-at-the-system-level-aka-end-to-end-tests).
+
 [multiple pieces]: ../architecture.md#components
 [GitLab Shell]: https://gitlab.com/gitlab-org/gitlab-shell
 [GitLab Workhorse]: https://gitlab.com/gitlab-org/gitlab-workhorse

qa/README.md

-# GitLab QA - Integration tests for GitLab
+# GitLab QA - End-to-end tests for GitLab
 
-This directory contains integration tests for GitLab.
+This directory contains [end-to-end tests](doc/development/testing_guide/end_to_end_tests.md)
+for GitLab. It includes the test framework and the tests themselves.
+
+The tests can be found in `qa/specs/features` (not to be confused with the unit
+tests for the test framework, which are in `spec/`).
 
 It is part of the [GitLab QA project](https://gitlab.com/gitlab-org/gitlab-qa).
 
 ## What is it?
 
-GitLab QA is an integration tests suite for GitLab.
+GitLab QA is an end-to-end tests suite for GitLab.
 
-These are black-box and entirely click-driven integration tests you can run
+These are black-box and entirely click-driven end-to-end tests you can run
 against any existing instance.
 
 ## How does it work?
 
 1. When we release a new version of GitLab, we build a Docker images for it.
 1. Along with GitLab Docker Images we also build and publish GitLab QA images.
-1. GitLab QA project uses these images to execute integration tests.
+1. GitLab QA project uses these images to execute end-to-end tests.
 
 ## Validating GitLab views / partials / selectors in merge requests