Remove cb prefix from cookbook entries since they're already in /cookbook/ directory

docs/cookbook/01-introduction-tip.md renamed

docs/cookbook/01-introduction.md renamed

docs/cookbook/02-inline-styles tip.md renamed

docs/cookbook/02-inline-styles.md renamed

docs/cookbook/03-if-else-in-JSX tip.md renamed

docs/cookbook/03-if-else-in-JSX.md renamed

docs/cookbook/04-self-closing-tag tip.md renamed

docs/cookbook/04-self-closing-tag.md renamed

docs/cookbook/05-jsx-root-node-count tip.md renamed

docs/cookbook/05-jsx-root-node-count.md renamed

docs/cookbook/06-style-prop-value-px tip.md renamed

docs/cookbook/06-style-prop-value-px.md renamed

docs/cookbook/07-children-prop-type tip.md renamed

docs/cookbook/07-children-prop-type.md renamed

docs/cookbook/08-controlled-input-null-value tip.md renamed

docs/cookbook/08-controlled-input-null-value.md renamed

docs/cookbook/09-componentWillReceiveProps-not-triggered-after-mounting-tip.md renamed

docs/cookbook/09-componentWillReceiveProps-not-triggered-after-mounting.md renamed

docs/cookbook/10-props-in-getInitialSate-as-anti-pattern-tip.md renamed

docs/cookbook/10-props-in-getInitialSate-as-anti-pattern.md renamed

docs/cookbook/11-dom-event-listeners tip.md renamed

docs/cookbook/11-dom-event-listeners.md renamed

docs/cookbook/12-initial-ajax tip.md renamed

docs/cookbook/12-initial-ajax.md renamed