Document :exclude tag in E2E testing docs

See https://gitlab.com/gitlab-org/quality/team-tasks/-/issues/947

doc/development/testing_guide/end_to_end/environment_selection.md

@@ -66,3 +66,24 @@ Similarly to specifying that a test should only run against a specific environme
 test only when it runs against a specific environment. The syntax is exactly the same, except that the `only: { ... }`
 hash is nested in the [`quarantine: { ... }`](https://about.gitlab.com/handbook/engineering/quality/guidelines/debugging-qa-test-failures/#quarantining-tests) hash.
 For instance, `quarantine: { only: { subdomain: :staging } }` only quarantines the test when run against staging.
+
+## Excluding a test from running in a particular job
+
+Sometimes we need to skip a test in a particular job but allow it to run in other jobs of the same pipeline or environment.
+We can do it with the help of `exclude` metadata.
+
+Examples:
+
+```ruby
+RSpec.describe 'Excluding' do
+  it 'skips given a single named job', exclude: { job: 'ee:instance-image' } do; end
+
+  it 'skips given a single regex pattern', exclude: { job: '.*:instance-image' } do; end
+
+  it 'skips given an array of jobs', exclude: { job: %w[ee:instance-image qa-schedules-browser_ui-3_create] } do; end
+
+  it 'skips given an array of regex patterns', exclude: { job: %w[ee:.* qa-schedules-browser_ui.*] } do; end
+
+  it 'skips given a mix of strings and regex patterns', exclude: { job: %w[ee:instance-image qa-schedules-browser_ui.*] } do; end
+end
+```

doc/development/testing_guide/end_to_end/rspec_metadata_tests.md

@@ -14,6 +14,7 @@ This is a partial list of the [RSpec metadata](https://relishapp.com/rspec/rspec
 | Tag | Description |
 |-----|-------------|
 | `:elasticsearch`  | The test requires an Elasticsearch service. It is used by the [instance-level scenario](https://gitlab.com/gitlab-org/gitlab-qa#definitions) [`Test::Integration::Elasticsearch`](https://gitlab.com/gitlab-org/gitlab/-/blob/72b62b51bdf513e2936301cb6c7c91ec27c35b4d/qa/qa/ee/scenario/test/integration/elasticsearch.rb) to include only tests that require Elasticsearch. |
+| `:exclude`        | The test is excluded from running in a specific job. See [Environment selection](environment_selection.md#excluding-a-test-from-running-in-a-particular-job) for more information. |
 | `:geo`            | The test requires two GitLab Geo instances - a primary and a secondary - to be spun up. |
 | `:gitaly_cluster` | The test runs against a GitLab instance where repositories are stored on redundant Gitaly nodes behind a Praefect node. All nodes are [separate containers](../../../administration/gitaly/praefect.md#requirements-for-configuring-a-gitaly-cluster). Tests that use this tag have a longer setup time since there are three additional containers that need to be started. |
 | `:github`         | The test requires a GitHub personal access token. |