auto merge of #13587 : adrientetar/rust/more-docs, r=brson

- Use Fira Sans for headlines, Heuristica for the body (Adobe Utopia derivative). Both are licensed under the SIL OFL license. (I didn't include BoldItalic because it is sparingly used.)
- Split TOC into 2 columns for the docs except manual (too tall, too wide to be readable).
- Some fixes to rustdoc, bring styles in coherency with eachother
- A few tweaks

Two examples: [modified tutorial](http://adrientetar.legtux.org/cached/rust-docs/tutorial.htm) and [modified manual](http://adrientetar.legtux.org/cached/rust-docs/manual.htm).

Rustdoc got some fixes, here is [modified `enum.FileType`](http://adrientetar.legtux.org/cached/rust-docs/enum.FileType.htm), [modified `std`](http://adrientetar.legtux.org/cached/rust-docs/std.htm) and [modified `std::io`](http://adrientetar.legtux.org/cached/rust-docs/io.htm).

#13484, #13485 follow-up.

cc @brson

1 files changed, 1 insertions, 1 deletions

diff --git a/src/doc/guide-tasks.md b/src/doc/guide-tasks.md
index ed5384830d9..26e5c053372 100644
--- a/src/doc/guide-tasks.md
+++ b/src/doc/guide-tasks.md
@@ -456,7 +456,7 @@ an `Error` result.
 
 [`Result`]: std/result/index.html
 
-> ***Note:*** A failed task does not currently produce a useful error
+> *Note:* A failed task does not currently produce a useful error
 > value (`try` always returns `Err(())`). In the
 > future, it may be possible for tasks to intercept the value passed to
 > `fail!()`.