fix contribute page anchor position shifted (#18571)
fix contribute page anchor position shifted (#18571)

Co-authored-by: Yang Shi <8284d488177dabe6514fec7c25e75298459823d2@amazon.com>
leezu/mxnet,apache/incubator-mxnet,tlby/mxnet,tlby/mxnet,leezu/mxnet,szha/mxnet,leezu/mxnet,apache/incubator-mxnet,szha/mxnet,yajiedesign/mxnet,szha/mxnet,sxjscience/mxnet,sxjscience/mxnet,apache/incubator-mxnet,tlby/mxnet,tlby/mxnet,tlby/mxnet,tlby/mxnet,szha/mxnet,leezu/mxnet,tlby/mxnet,tlby/mxnet,yajiedesign/mxnet,yajiedesign/mxnet,leezu/mxnet,szha/mxnet,szha/mxnet,DickJC123/mxnet,tlby/mxnet,leezu/mxnet,sxjscience/mxnet,szha/mxnet,sxjscience/mxnet,yajiedesign/mxnet,DickJC123/mxnet,sxjscience/mxnet,sxjscience/mxnet,leezu/mxnet,leezu/mxnet,sxjscience/mxnet,leezu/mxnet,szha/mxnet,sxjscience/mxnet,yajiedesign/mxnet,tlby/mxnet,apache/incubator-mxnet,szha/mxnet,DickJC123/mxnet,sxjscience/mxnet,DickJC123/mxnet,yajiedesign/mxnet,yajiedesign/mxnet,yajiedesign/mxnet,yajiedesign/mxnet