Add long error explanation for E0710

src/librustc_error_codes/error_codes.rs

@@ -393,6 +393,7 @@ E0701: include_str!("./error_codes/E0701.md"),
 E0704: include_str!("./error_codes/E0704.md"),
 E0705: include_str!("./error_codes/E0705.md"),
 E0706: include_str!("./error_codes/E0706.md"),
+E0710: include_str!("./error_codes/E0710.md"),
 E0712: include_str!("./error_codes/E0712.md"),
 E0713: include_str!("./error_codes/E0713.md"),
 E0714: include_str!("./error_codes/E0714.md"),
@@ -604,7 +605,6 @@ E0748: include_str!("./error_codes/E0748.md"),
     E0708, // `async` non-`move` closures with parameters are not currently
            // supported
 //  E0709, // multiple different lifetimes used in arguments of `async fn`
-    E0710, // an unknown tool name found in scoped lint
     E0711, // a feature has been declared with conflicting stability attributes
     E0717, // rustc_promotable without stability attribute
 //  E0721, // `await` keyword

src/librustc_error_codes/error_codes/E0710.md

@@ -0,0 +1,34 @@
+An unknown tool name found in scoped lint
+
+Erroneous code examples:
+
+```compile_fail,E0710
+#[allow(clipp::filter_map)] // error!`
+fn main() {
+    // business logic
+}
+```
+
+```compile_fail,E0710
+#[warn(clipp::filter_map)] // error!`
+fn main() {
+    // business logic
+}
+```
+
+Please verify you didn't misspell the tool's name or that you didn't
+forget to import it in you project:
+
+```
+#[allow(clippy::filter_map)] // ok!
+fn main() {
+    // business logic
+}
+```
+
+```
+#[warn(clippy::filter_map)] // ok!
+fn main() {
+    // business logic
+}
+```

src/test/ui/tool_lints.stderr

@@ -18,3 +18,4 @@ LL | #[warn(foo::bar)]
 
 error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0710`.

src/test/ui/unknown-lint-tool-name.stderr

@@ -36,3 +36,4 @@ LL | #[allow(foo::bar)]
 
 error: aborting due to 6 previous errors
 
+For more information about this error, try `rustc --explain E0710`.