Merge branch '62971-embed-specific-metrics-chart-in-issue-docs' into 'master'

Embed specific metrics chart in issue docs

See merge request gitlab-org/gitlab-ce!31900

(cherry picked from commit aed489bf)

482642b0 Adds specific metric styles and prop
146243da Updated styles, removed css :D
0a5d49f7 Adds docs for embedding chart
4bbb0ddf Simpler null checks
758a195b Fix some wrapping issues
d6550ad4 Fix lint and prop type
675639cc Remove everything that isn't docs
eb27d0f1 Apply suggestion to doc/user/project/integrations/prometheus.md
364e7219 Compress generate_link_to_chart.png image

doc/user/project/integrations/prometheus.md

@@ -369,6 +369,10 @@ It is possible to display metrics charts within [GitLab Flavored Markdown](../..
 
 To display a metric chart, include a link of the form `https://<root_url>/<project>/environments/<environment_id>/metrics`.
 
+A single chart may also be embedded. You can generate a link to the chart via the dropdown located on the right side of the chart:  
+
+![Generate Link To Chart](img/generate_link_to_chart.png)
+
 The following requirements must be met for the metric to unfurl:
 
 - The `<environment_id>` must correspond to a real environment.