fix typo workerPoolMode (#6407)

## What's the problem this PR addresses?

incorrect spelling of option
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## How did you fix it?
fix the spelling
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Author: mifi

packages/docusaurus/static/configuration/yarnrc.json

@@ -810,7 +810,7 @@
       "type": "number",
       "default": "os.availableParallelism()"
     },
-    "workerPoolMode": {
+    "taskPoolMode": {
       "_package": "@yarnpkg/core",
       "title": "Execution strategy for heavy tasks.",
       "description": "By default will use workers when performing heavy tasks, such as converting tgz files to zip. This setting can be used to disable workers and use a regular in-thread async processing.",