sdk-manual: Updated the section on adding docs to standard SDK

Fixes [YOCTO #8584]

Made some edits to tighten this down and make it more efficient.

(From yocto-docs rev: d5a37b77fa5c8df766248849601ca229502bb4ab)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/sdk-manual/sdk-appendix-customizing-standard.xml

@@ -21,7 +21,7 @@
          <ulink url='&YOCTO_DOCS_REF_URL;#var-TOOLCHAIN_HOST_TASK'><filename>TOOLCHAIN_HOST_TASK</filename></ulink>
          and
          <ulink url='&YOCTO_DOCS_REF_URL;#var-TOOLCHAIN_TARGET_TASK'><filename>TOOLCHAIN_TARGET_TASK</filename></ulink>
-         variables contol the set of packages adding to the SDK.
+         variables control the set of packages adding to the SDK.
     </para>
 
     <para>
@@ -38,22 +38,17 @@
     <title>Adding API Documentation to the Standard SDK</title>
 
     <para>
-        You might want to include documentation as part of the standard SDK.
-        For example, you might want the API documentation to be built and
-        included with the SDK.
-        You can include API documentation as well as any other documentation
-        with the standard SDK by setting the
-        <ulink url='&YOCTO_DOCS_REF_URL;#var-SDKIMAGE_FEATURES'><filename>SDKIMAGE_FEATURES</filename></ulink>
-        and
+        You can include API documentation as well as any other
+        documentation provided by recipes with the standard SDK by
+        adding "api-documentation" to the
         <ulink url='&YOCTO_DOCS_REF_URL;#var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></ulink>
-        variables:
+        variable:
         <literallayout class='monospaced'>
-     SDKIMAGE_FEATURES = "doc-pkgs"
-     DISTRO_FEATURES = "api-documentation"
+     DISTRO_FEATURES_append = " api-documentation"
         </literallayout>
-        Setting these variables as shown here causes the OpenEmbedded build
-        system to build the documentation and then include it in the
-        standard SDK.
+        Setting this variable as shown here causes the OpenEmbedded build
+        system to build the documentation and then include it in the standard
+        SDK.
     </para>
 </section>