readme: move to shields.io and format (#70)
readme: move to shields.io and format (#70)

* readme: move to shields.io and format

* readme: add image-size
ustclug/ustcmirror-images,ustclug/ustcmirror-images,ustclug/ustcmirror-images,ustclug/ustcmirror-images,ustclug/ustcmirror-images