fix: link to ipfs.io

Author: Alan Shaw

README.md

@@ -1,5 +1,5 @@
 <h1 align="center">
-  <a href="ipfs.io"><img width="650px" src="https://ipfs.io/ipfs/QmQJ68PFMDdAsgCZvA1UVzzn18asVcf7HVvCDgpjiSCAse" alt="IPFS http client lib logo" /></a>
+  <a href="https://ipfs.io"><img width="650px" src="https://ipfs.io/ipfs/QmQJ68PFMDdAsgCZvA1UVzzn18asVcf7HVvCDgpjiSCAse" alt="IPFS http client lib logo" /></a>
 </h1>
 
 <h3 align="center">The JavaScript HTTP client library for IPFS implementations.</h3>