Added new CDN - PageCDN
Added new CDN - PageCDN

PageCDN uses brotli-11 compression that reduces cytoscape's file sizes by upto 28 KBs compared to other CDNs. In addition, immutable caching is enabled by default to optimize content delivery a little more aggressively. This will make PageCDN a valuable addition to the documentation.

Thanks.
cytoscape/cytoscape.js,cytoscape/cytoscape.js