fix: Preserve @example titles

[Josmithr]

Summary

Per TSDoc's documented spec, text on the same line as an @example tag is considered the title for the example. The parser previously discarded it. This PR parses the title, exposes it on the AST, and preserves it on round-trip emission.

Round-tripping an @example block would previously result in the title context being lost. It is now preserved.

Input	Previous Output (incorrect line formatting)	New Output (preserves necessary line formatting)
/** * Summary. * * @example Adding two numbers * ```ts * add(1, 2); * ``` */	/** * Summary. * * @example * * Adding two numbers * ```ts * add(1, 2); * ``` */	/** * Summary. * * @example Adding two numbers * ```ts * add(1, 2); * ``` */

Changes

• New DocExampleBlock node with a title. Registered in DocNodeKind, BuiltInDocNodes, and exported.
• Parser: @example now captures the same-line text as the title and routes the rest into the content section.
• Emitter: re-emits the title on the tag line, preserving layout.

Notes

• Titles are plain-text only for now; inline-tags are not parsed as anything but plain text. The spec is ambiguous about this - support for inline tag parsing could be added if desired.

[Josmithr]

@octogonz I took a stab at resolving microsoft/rushstack#4860. Would love your feedback when you have a moment.