Add concept page for CLA assistant (#302)

* Add concept page for CLA assistant

Explain the purpose for the CLA assistant and how to trigger the workflow if it does not report automatically.

Signed-off-by: Jack Baldry <jack.baldry@grafana.com>

* Prettier

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Apply technical writer suggestions

Co-authored-by: Isabel <76437239+imatwawana@users.noreply.github.com>

---------

Signed-off-by: Jack Baldry <jack.baldry@grafana.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Isabel <76437239+imatwawana@users.noreply.github.com>

docs/sources/review/cla-assistant/index.md

@@ -0,0 +1,42 @@
+---
+title: About CLA assistant
+description: Understand the CLA assistant and its use on GitHub pull requests.
+---
+
+# About CLA assistant
+
+[CLA assistant](https://cla-assistant.io/) is used by Grafana Labs to ensure that all contributors to a GitHub pull request (PR) have signed the Grafana Labs Contributor License Agreement (CLA).
+
+Grafana Labs doesn't operate the CLA assistant infrastructure; instead it's provided by SAP.
+The CLA assistant project is open source and you can find the source code in the [cla-assistant repository](https://github.com/cla-assistant/cla-assistant).
+
+The workflow runs automatically on all PRs.
+During periods of high load on the CLA assistant infrastructure, the workflow can fail to report a status.
+If it doesn't report back and all other continuous integration (CI) checks have completed, follow the directions in [Waiting for status to be reported](#waiting-for-status-to-be-reported) to rerun the workflow.
+
+{{% admonition type="note" %}}
+During prolonged periods of high load on the CLA assistant infrastructure, even rerunning the workflow might not result in a successful status.
+In this case, wait a few hours and try again later.
+{{% /admonition %}}
+
+## Waiting for status to be reported
+
+<!-- vale Grafana.WordList = NO -->
+<!-- "check" here is used as a noun not a verb. TODO: update the WordList to only lint "check" as a verb. -->
+
+Occasionally, the CLA assistant workflow isn't reported on an open PR, preventing the PR from being merged.
+You can request that the CLA assistant run again by browsing to the check URL for the PR.
+
+<!-- vale Grafana.WordList = YES -->
+
+The format of the URL is `https://cla-assistant.io/check/grafana/<REPOSITORY>?pullRequest=<PR>`.
+
+- _`REPOSITORY`_ is the GitHub repository name.
+- _`PR`_ is the pull request number in the repository.
+
+For example, to trigger the CLA assistant workflow for the pull request `https://github.com/grafana/grafana/pull/1`, the URL is `https://cla-assistant.io/check/grafana/grafana?pullRequest=1`.
+
+{{% admonition type="note" %}}
+The URL redirects your browser back to https://github.com without any feedback suggesting the workflow has been triggered.
+After a few minutes, check the PR to see if the status has been reported.
+{{% /admonition %}}