Fix spelling of FiraSans-*.woff2

Author: Nemo157

src/docbuilder/rustwide_builder.rs

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