Issue #3444468: Updates documentation and test scripts for clarity

I wanted to make the docs a little easier to read and do a little test script tidying.

1. The main README.md has more styling a few language changes
2. The script README.md has line breaks removed
3. The 10000-item script has been renamed for clarity. Maybe it's my bad eyes, but TestDo10kThings.php and TestDo10Things.php were harder to distinguish.
4. The language of the script logs and comments has been more aligned with their intention or content.

src/Drush/Commands/CoditBatchOperationsCommands.php

@@ -28,7 +28,7 @@ final class CoditBatchOperationsCommands extends DrushCommands implements Contai
    */
   public function __construct(
     private readonly Token $token,
-    ConfigFactoryInterface $config_factory
+    ConfigFactoryInterface $config_factory,
   ) {
     parent::__construct();
     $this->configFactory = $config_factory;
@@ -103,7 +103,7 @@ final class CoditBatchOperationsCommands extends DrushCommands implements Contai
     $test_scripts = [
       'TestDo10Things',
       'TestDo10ThingsWithError',
-      'TestDo10kThings',
+      'TestDo10000Things',
     ];
     if (in_array($script, $test_scripts)) {
       // This is a test script, so route it to codit_batch_operations.