docs(guide/concepts): removed div-clear-tags breaking the formatting

[Silwing]

The concepts page of the docs (http://docs.angularjs.org/guide/concepts) is half unreadable due to formatting not being parsed properly.

It can be solved by removing <div class="clear"></div> from the concepts.ng, which I did in this PR.

[mary-poppins]

Thanks for the PR!

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Thanks again for your help!

[Silwing]

My real name is Randi Katrine Hillerøe and I just signed the CLA a few hours ago.

[petebacondarwin]

Thanks @Silwing - I just had to tweak the commit message slightly - we don't use past tense.

[Silwing]

Ah, I'm still learning this whole git pull request thing :) I fixed the tense in my commit but apparantly I needed to fix it separately for the PR as well.