Clean up E0466 explanation

GuillaumeGomez · GuillaumeGomez · commit 194a3718ab20 · 2020-03-31T13:55:58.000+02:00
diff --git a/src/librustc_error_codes/error_codes/E0466.md b/src/librustc_error_codes/error_codes/E0466.md
@@ -1,4 +1,4 @@
-Macro import declarations were malformed.
+Macro import declaration was malformed.
 
 Erroneous code examples:
 

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-Macro import declarations were malformed.`
	`1`	`+Macro import declaration was malformed.`
`2`	`2`
`3`	`3`	`Erroneous code examples:`
`4`	`4`