Clean up E0710 explanation

GuillaumeGomez · GuillaumeGomez · commit 69d5fc1a9f89 · 2020-07-02T15:44:22.000+02:00
diff --git a/src/librustc_error_codes/error_codes/E0710.md b/src/librustc_error_codes/error_codes/E0710.md
@@ -1,4 +1,4 @@
-An unknown tool name found in scoped lint
+An unknown tool name was found in a scoped lint.
 
 Erroneous code examples:
 

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-An unknown tool name found in scoped lint`
	`1`	`+An unknown tool name was found in a scoped lint.`
`2`	`2`
`3`	`3`	`Erroneous code examples:`
`4`	`4`