dedup "thread-mute" page link / "スレッドミュート" ページへのリンクの重複排除

[thinceller]

Why

Currently "thread-mute" links in nav bar are duplicated. 現在、ナビゲーションバー内の「スレッドミュート」リンクが重複して存在しています

• https://github.com/misskey-dev/misskey-hub/blob/8f790cdc8d383f1132094d14a518e4b0aa2fba31/src/.vuepress/config.ts#L97-L107
• https://github.com/misskey-dev/misskey-hub/blob/8f790cdc8d383f1132094d14a518e4b0aa2fba31/src/.vuepress/config.ts#L182-L192
• https://github.com/misskey-dev/misskey-hub/blob/8f790cdc8d383f1132094d14a518e4b0aa2fba31/src/.vuepress/config.ts#L356-L366

What

Deduplicate '/docs/features/thread-mute' link in src/.vuepress/config.ts src/.vuepress/config.ts 内の '/docs/features/thread-mute' リンクの重複を排除

before	after

[syuilo]

🙏