Update docs for brownfield configuration path to be app.security.pattern

[aurabirb]

Description

• This MR updates the documentation for tauri.conf.json for the Brownfield config which references an outdated Tauri 1.0 tauri > pattern config setting.
  This MR updates this path to the one used in Tauri 2.x: app > security > pattern.
  The relevant upgrade docs are here: https://tauri.app/start/migrate/from-tauri-1/

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