ref-manual: Document the task feature of BUILDHISTORY_FEATURES

index 521eaeaed2..70e5e3428b 100644
@@ -1927,8 +1927,8 @@
                 </para>
 
                 <para>
-                    You can specify three features in the form of a
-                    space-separated list:
+                    You can specify features in the form of a space-separated
+                    list:
                     <itemizedlist>
                         <listitem><para><emphasis>image:</emphasis>
                             Analysis of the contents of images, which

@@ -1942,12 +1942,17 @@
                             Analysis of the contents of the software
                             development kit (SDK).
                             </para></listitem>
+                        <listitem><para><emphasis>task:</emphasis>
+                            Save output file signatures for sstate tasks.  This
+                            saves a file per task listing the SHA-256 checksums
+                            for each file staged, i.e., the output of the task.
+                            </para></listitem>
                     </itemizedlist>
                 </para>
 
                 <para>
                     By default, the <filename>buildhistory</filename> class
-                    enables all three features:
+                    enables the following features:
                     <literallayout class='monospaced'>
      BUILDHISTORY_FEATURES ?= "image package sdk"
                     </literallayout>