[docs][pipeline-connector][paimon] fix example bug for `Paimon 'wareh…

[beryllw]

fix example bug for Paimon 'warehouse' path must be set

[beryllw]

When I use paimon sink I encounter a bug.Looks like this is an incorrect attribute setting in Example yaml.

Exception in thread "main" java.lang.RuntimeException: failed to create or use paimon catalog
        at org.apache.flink.cdc.connectors.paimon.sink.PaimonDataSinkFactory.createDataSink(PaimonDataSinkFactory.java:72)
        at org.apache.flink.cdc.composer.flink.FlinkPipelineComposer.createDataSink(FlinkPipelineComposer.java:164)
        at org.apache.flink.cdc.composer.flink.FlinkPipelineComposer.compose(FlinkPipelineComposer.java:129)
        at org.apache.flink.cdc.cli.CliExecutor.run(CliExecutor.java:71)
        at org.apache.flink.cdc.cli.CliFrontend.main(CliFrontend.java:71)
Caused by: java.lang.NullPointerException: Paimon 'warehouse' path must be set
        at org.apache.paimon.utils.Preconditions.checkNotNull(Preconditions.java:65)
        at org.apache.paimon.catalog.CatalogFactory.warehouse(CatalogFactory.java:55)
        at org.apache.paimon.catalog.CatalogFactory.createCatalog(CatalogFactory.java:83)
        at org.apache.paimon.catalog.CatalogFactory.createCatalog(CatalogFactory.java:66)
        at org.apache.paimon.flink.FlinkCatalogFactory.createPaimonCatalog(FlinkCatalogFactory.java:80)
        at org.apache.flink.cdc.connectors.paimon.sink.PaimonDataSinkFactory.createDataSink(PaimonDataSinkFactory.java:68)
        ... 4 more

When I correct metastore and warehouse to catalog.properties.xxx, it's OK. @lvyanquan cc, thank you.