Update README to point to the Getting Started guide in the repo.
Update README to point to the Getting Started guide in the repo.

Review URL: http://codereview.chromium.org/1649003

git-svn-id: e22621a84199d42b34715cdc089545aeedbbf23f@187 050acbb0-2703-11df-ab0a-9f3f633ae91d

sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk