fix version in legacy footer

archivebox/themes/default/main_index.html

@@ -243,7 +243,7 @@
             <center>
                 <small>
                     Archive created using <a href="https://github.com/ArchiveBox/ArchiveBox" title="Github">ArchiveBox</a>
-                    version <a href="https://github.com/ArchiveBox/ArchiveBox/tree/v{{VERSION}}" title="Git commit">v{{VERSION}}</a> &nbsp; | &nbsp; 
+                    version <a href="https://github.com/ArchiveBox/ArchiveBox/tree/v{{version}}" title="Git commit">v{{version}}</a> &nbsp; | &nbsp; 
                     Download index as <a href="index.json" title="JSON summary of archived links.">JSON</a>
                     <br/><br/>
                     {{FOOTER_INFO}}