Add woff2 fonts to essential files unversioned

Author: dtolnay

src/docbuilder/rustwide_builder.rs

@@ -47,7 +47,9 @@ const ESSENTIAL_FILES_VERSIONED: &[&str] = &[
 ];
 const ESSENTIAL_FILES_UNVERSIONED: &[&str] = &[
     "FiraSans-Medium.woff",
+    "FireSans-Medium.woff2",
     "FiraSans-Regular.woff",
+    "FireSans-Regular.woff2",
     "SourceCodePro-Regular.woff",
     "SourceCodePro-Semibold.woff",
     "SourceSerifPro-Bold.ttf.woff",