[yocto] clashing explanations of EXTRA_IMAGE_FEATURES in dev manual

[Robert P. J. Day]

  i'll let scott :-) reword this how he prefers, but in the dev
manual, there's this in section 5.10.6.1:
http://www.yoctoproject.org/docs/latest/dev-manual/dev-manual.html#testing-packages-with-ptest

     EXTRA_IMAGE_FEATURES += "ptest-pkgs"

while just a bit further down in section 5.15.1:
http://www.yoctoproject.org/docs/latest/dev-manual/dev-manual.html#creating-the-root-filesystem

one reads:

     IMAGE_FEATURES = "read-only-rootfs"

or

     EXTRA_IMAGE_FEATURES = "read-only-rootfs"

  i think readers might get confused as to when to use one or the
other variable, and whether to use "=" or "+=".

rday

-- 

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
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