By Sarah McBride SAN FRANCISCO (Reuters) – Nextdoor, an online social network for neighbors, said it has attracted $60 million from early backers of technology titans Google, Amazon and Facebook. The new investment, led by venture firm Kleiner Perkins Caufield Byers and investment firm Tiger Global Management, values Nextdoor at more than $500 million, said a person familiar with the matter. Nextdoor members make Facebook-style postings, giving or seeking recommendations for services such as babysitters and yard maintenance or local retailers and restaurants. …