docs(adventure): explain multiline item lore

[spa77k]

Closes #670.

Adds a short FAQ on constructing item lore one line at a time, with a MiniMessage example for a list of configured strings. The localization guide has a matching example using a translation key for each line.

The examples avoid splitting an already-built component. The FAQ also notes that formatting is independent for each line. The existing warning about platform limitations on automatic item translation is unchanged.

Verification:

• Ran both examples against Adventure 5.2.0 on Java 21. Checked the two entries, their independent styles (including a negative control), and both translation keys.
• git diff --check passed.
• pnpm format:check passed (Markdown files are excluded by the repository's .prettierignore).
• Dependency installation completed, but the local site build was killed with exit code 137 during content sync. Leaving this as a draft while the preview build runs in CI.

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