Update README for GITTIP_CSS_HREF
Update README for GITTIP_CSS_HREF

mccolgst/www.gittip.com,gratipay/gratipay.com,gratipay/gratipay.com,mccolgst/www.gittip.com,eXcomm/gratipay.com,gratipay/gratipay.com,eXcomm/gratipay.com,studio666/gratipay.com,studio666/gratipay.com,mccolgst/www.gittip.com,mccolgst/www.gittip.com,eXcomm/gratipay.com,gratipay/gratipay.com,studio666/gratipay.com,studio666/gratipay.com,eXcomm/gratipay.com