feat: Update CityJSON extension version to 0.2.0 and enhance documentation

[HideBa]

Updates the cityjson community extension to v0.2.0 (DuckDB v1.5.4).

Since 0.1.0 the extension has gained:

• Write support via COPY ... TO (cityjson, cityjsonseq, flatcitybuf)
• Wide columnar layout: one WKB geometry column per LOD, plus a per-object bbox
• Filter pushdown on id, feature_id, object_type
• Streaming reads of large CityJSONSeq and remote (HTTP/S3/GCS) files
• FlatCityBuf (.fcb) read/write

Bumps version to 0.2.0 and ref to the latest release commit.

[carlopi]

Thanks!