src/main/java/com/google/devtools/build/docgen/templates/attributes/common/features.html

<p><code>List of <i>feature</i> strings; optional</code></p>

<p>A feature is string tag that can be enabled or disabled on a target. The
  meaning of a feature depends on the rule itself.</p>

<p>This <code>features</code> attribute is combined with the <a href="${link package}">
package</a> level <code>features</code> attribute. For example, if
the features ["a", "b"] are enabled on the package level, and a target's
<code>features</code> attribute contains ["-a", "c"], the features enabled for the
rule will be "b" and "c".
  <a href="https://github.com/bazelbuild/examples/blob/main/rules/features/BUILD">
    See example</a>.
</p>