doc: use correct body font URLs

The CSS for the docs homepage (docs.rust-lang.org) was using the wrong
URL for the body font, resulting in the fallback serif font being used,
instead of the desired Source Serif Pro fonts.

Author: benesch

src/doc/rust.css

@@ -14,19 +14,19 @@
 	font-family: 'Source Serif Pro';
 	font-style: normal;
 	font-weight: 400;
-	src: local('Source Serif Pro'), url("SourceSerifPro-Regular.woff") format('woff');
+	src: local('Source Serif Pro'), url("SourceSerifPro-Regular.ttf.woff") format('woff');
 }
 @font-face {
 	font-family: 'Source Serif Pro';
 	font-style: italic;
 	font-weight: 400;
-	src: url("Heuristica-Italic.woff") format('woff');
+	src: url("SourceSerifPro-It.ttf.woff") format('woff');
 }
 @font-face {
 	font-family: 'Source Serif Pro';
 	font-style: normal;
 	font-weight: 700;
-	src: local('Source Serif Pro Bold'), url("SourceSerifPro-Bold.woff") format('woff');
+	src: local('Source Serif Pro Bold'), url("SourceSerifPro-Bold.ttf.woff") format('woff');
 }
 @font-face {
 	font-family: 'Source Code Pro';