warn about validation vs invalidation and cleanup feature list

[dbu]

fix #141

[dbu]

added "In addition" to make it clear that this is something different.

[dbu]

@ddeboer any idea why the build is failing with "Resources/doc/features/invalidation.rst:19: WARNING: undefined label: foshttpcache:invalidation-introduction (if the link has no caption the label must precede a section header)"? i do exactly the same thing as there is 3 lines above about proxy-configuration.

[ddeboer]

I think the ref should be invalidation introduction (without dash): https://raw.githubusercontent.com/FriendsOfSymfony/FOSHttpCache/master/doc/invalidation-introduction.rst (at the top).

[dbu]

I think the ref should be |invalidation introduction| (without underscore).

i used a hyphen, not an underscore. i looked at the proxy-configuration
3 lines above which works. removing the hyphen as you say indeed creates
me a link that works - no idea why. but well, i think we can merge now.

[ddeboer]

That’s because the ref is there called proxy-configuration (with dash): https://raw.githubusercontent.com/FriendsOfSymfony/FOSHttpCache/master/doc/proxy-configuration.rst. Not very consistent, I realise. 😉

Anyway, as long as this builds, we’re good to go.

[dbu]

aaahh. and i thought we can reference a file. well ok, now it all makes
sense :-)

[ddeboer]

Good to hear. :)