Fix citation href value for ETSI doc.

The `href` value MUST be a string. The array value breaks 
downstream tooling like the JSON-LD output for SEO (likely
among others).

Author: BigBlueHat

index.html

@@ -53,7 +53,7 @@
           },
           "ETSI-TRUST-LISTS": {
             title: "Electronic Signatures and Infrastructures (ESI); Trusted Lists",
-            href: ["https://www.etsi.org/deliver/etsi_ts/119600_119699/119612/02.01.01_60/ts_119612v020101p.pdf"],
+            href: "https://www.etsi.org/deliver/etsi_ts/119600_119699/119612/02.01.01_60/ts_119612v020101p.pdf",
             authors: ["ETSI"],
             status: "ETSI Standard TS 119 612 V2.1.1 (2015-07)",
             publisher: "ETSI"