clean up E0195 explanation

Author: GuillaumeGomez

src/librustc_error_codes/error_codes/E0195.md

@@ -1,4 +1,5 @@
-Your method's lifetime parameters do not match the trait declaration.
+The lifetime parameters of the method do not match the trait declaration.
+
 Erroneous code example:
 
 ```compile_fail,E0195
@@ -16,7 +17,7 @@ impl Trait for Foo {
 }
 ```
 
-The lifetime constraint `'b` for bar() implementation does not match the
+The lifetime constraint `'b` for `bar()` implementation does not match the
 trait declaration. Ensure lifetime declarations match exactly in both trait
 declaration and implementation. Example: