Tidied up E0637.md

Author: jwhite927

src/librustc_error_codes/error_codes/E0637.md

@@ -13,9 +13,9 @@ fn longest<'_>(str1: &'_ str, str2: &'_ str) -> &'_ str {
 ```
 `'_`, cannot be used as a lifetime identifier because it is a reserved for the
 anonymous lifetime. To fix this, use a lowercase letter such as 'a, or a series
-of lowercase letters such as `'foo`.  For more information, see [the book][bk-no].
-For more information on using the anonymous lifetime in rust nightly, see [the
-nightly book][bk-al].
+of lowercase letters such as `'foo`.  For more information, see [the
+book][bk-no].  For more information on using the anonymous lifetime in rust
+nightly, see [the nightly book][bk-al].
 
 Corrected example:
 ```