refactor: improve output messages (#404)

`Remove --check option to avoid this error` is a little ambiguous (e.g.,
will it just suppress the error). Updated to let the user know what will
happen if they remove it.

```sh
$ npx codeowners-generator generate --check
  
Custom configuration found in /Users/jared.mcateer/Projects/test/package.json
✖ We encountered an error: We found differences between the existing codeowners file and 
the generated rules. Remove --check option to fix this.
```

Added message for when `--check` is successful, rather than telling the
user the file was created, which should not happen with that command.

```sh
$ npx codeowners-generator generate --check
  
Custom configuration found in /Users/jared.mcateer/Projects/test/package.json
CODEOWNERS file up to date! location: .github/CODEOWNERS
```

Changed message for when new generated rules change the CO file, rather
than saying a file was created, let them know the generated rules have
changed. A CO file being created should be incredibly rare (i.e., maybe
the first time this tool is run in a project).

```sh
$ npx codeowners-generator generate

Custom configuration found in /Users/jared.mcateer/Projects/test/package.json
CODEOWNERS file updated with the generated rules! location: .github/CODEOWNERS
````

src/commands/generate.ts

@@ -157,13 +157,14 @@ export const command = async (options: Options, command: Command): Promise<void>
       if (check) {
         if (originalContent.trimEnd() !== newContent) {
           throw new Error(
-            'We found differences between the existing codeowners file and the generated. Remove --check option to avoid this error'
+            'We found differences between the existing codeowners file and the generated rules. Remove --check option to fix this.'
           );
         }
       } else {
         fs.writeFileSync(output, newContent);
       }
-      loader.stopAndPersist({ text: `CODEOWNERS file was created! location: ${output}`, symbol: SUCCESS_SYMBOL });
+      const message = check ? `up to date` : 'updated with the generated rules';
+      loader.stopAndPersist({ text: `CODEOWNERS file ${message}! location: ${output}`, symbol: SUCCESS_SYMBOL });
     } else {
       const includes = globalOptions.includes?.length ? globalOptions.includes : INCLUDES;
       loader.stopAndPersist({