fixup: E028 wording (#531)

crates/rover-client/src/error.rs

@@ -78,7 +78,7 @@ pub enum RoverClientError {
         if let Some(url) = .url {
             url.to_string()
         } else {
-            "Unknown URL".to_string()
+            "unknown URL".to_string()
         }
     )]
     CouldNotConnect {

docs/source/errors.md

@@ -229,8 +229,8 @@ To resolve this error, inspect the printed errors and correct the subgraph schem
 
 ### E028
 
-This error occurs when a connection could not be established with to an introspection endpoint.
+This error occurs when Rover could not connect to an HTTP endpoint.
 
-To resolve this problem, make sure the endpoint URL is correct. You may wish to run the command again with `--log=debug`.
+If you encountered this error while running introspection, you'll want to make sure that you typed the endpoint correctly, your Internet connection is stable, and that your server is responding to requests. You may wish to run the command again with `--log=debug`.
 
 

src/error/metadata/codes/E028.md

@@ -1,3 +1,3 @@
-This error occurs when a connection could not be established with to an introspection endpoint.
+This error occurs when Rover could not connect to an HTTP endpoint.
 
-To resolve this problem, make sure the endpoint URL is correct. You may wish to run the command again with `--log=debug`.
+If you encountered this error while running introspection, you'll want to make sure that you typed the endpoint correctly, your Internet connection is stable, and that your server is responding to requests. You may wish to run the command again with `--log=debug`.

src/error/metadata/suggestion.rs

@@ -125,7 +125,7 @@ impl Display for Suggestion {
                 )
             }
             Suggestion::Adhoc(msg) => msg.to_string(),
-            Suggestion::CheckServerConnection => "Make sure the endpoint accepting connections is spelled correctly".to_string(),
+            Suggestion::CheckServerConnection => "Make sure the endpoint is accepting connections and is spelled correctly".to_string(),
             Suggestion::ConvertGraphToSubgraph => "If you are sure you want to convert a non-federated graph to a subgraph, you can re-run the same command with a `--convert` flag.".to_string(),