Rollup merge of #40819 - donniebishop:master, r=alexcrichton

Link ParseBoolError to from_str method of bool

Referencing task in #29375. Sorry for not opening another branch on my fork for this. Was working on this early this morning and forgot to branch off master

src/libcore/str/mod.rs

@@ -101,7 +101,9 @@ fn from_str(s: &str) -> Result<bool, ParseBoolError> {
     }
 }
 
-/// An error returned when parsing a `bool` from a string fails.
+/// An error returned when parsing a `bool` using [`from_str`] fails
+///
+/// [`from_str`]: ../../std/primitive.bool.html#method.from_str
 #[derive(Debug, Clone, PartialEq, Eq)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct ParseBoolError { _priv: () }