Rollup merge of rust-lang#59405 - benesch:docs-font, r=GuillaumeGomez

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.

(It's worth noting that the CSS for rustdoc's API generation got these URLs right.)

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';