Small cleanup for E0705 explanation

GuillaumeGomez · GuillaumeGomez · commit 99c15133638c · 2020-06-27T13:07:59.000+02:00
diff --git a/src/librustc_error_codes/error_codes/E0705.md b/src/librustc_error_codes/error_codes/E0705.md
@@ -1,5 +1,5 @@
-A `#![feature]` attribute was declared for a feature that is stable in
-the current edition, but not in all editions.
+A `#![feature]` attribute was declared for a feature that is stable in the
+current edition, but not in all editions.
 
 Erroneous code example:
 
