Capitalise 'Apps' in 'Chrome Apps'.
Capitalise 'Apps' in 'Chrome Apps'.

'Chrome Apps' is consistently capitalised in the Chrome Apps docs, but
lowercase in the README.

R=mgiuca@chromium.org

Review URL: https://codereview.chromium.org/1572233002 .

chromium/caterpillar,chromium/caterpillar,chromium/caterpillar