[SPARK-40665][CONNECT][MINOR] Update README for a correct example to run tests for CONNECT
[SPARK-40665][CONNECT][MINOR] Update README for a correct example to run tests for CONNECT

### What changes were proposed in this pull request?

Correct the example in README for how to run CONNECT tests.

### Why are the changes needed?

This is a follow up minor update after https://github.com/apache/spark/pull/38109

### Does this PR introduce _any_ user-facing change?

No

### How was this patch tested?

N/A

Closes #38126 from amaliujia/update_read_me.

Authored-by: Rui Wang <5520b64c3217afc10cb881636dce6d49816c0d83@databricks.com>
Signed-off-by: Hyukjin Kwon <2680965ad5aae29275c8fb10150cb10f5554e78b@apache.org>

dongjoon-hyun/spark,mahak/spark,vinodkc/spark,ueshin/apache-spark,ueshin/apache-spark,zzcclp/spark,ueshin/apache-spark,apache/spark,wangyum/spark,wangyum/spark,mahak/spark,srowen/spark,hvanhovell/spark,dongjoon-hyun/spark,hvanhovell/spark,srowen/spark,vinodkc/spark,HyukjinKwon/spark,zzcclp/spark,apache/spark,hvanhovell/spark,mahak/spark,zzcclp/spark,vinodkc/spark,vinodkc/spark,shaneknapp/spark,ueshin/apache-spark,shaneknapp/spark,wangyum/spark,dongjoon-hyun/spark,hvanhovell/spark,mahak/spark,zzcclp/spark,zzcclp/spark,ueshin/apache-spark,ueshin/apache-spark,mahak/spark,zzcclp/spark,HyukjinKwon/spark,shaneknapp/spark,vinodkc/spark,apache/spark,hvanhovell/spark,dongjoon-hyun/spark,apache/spark,HyukjinKwon/spark,shaneknapp/spark,mahak/spark,apache/spark,srowen/spark,apache/spark,srowen/spark,srowen/spark,dongjoon-hyun/spark,HyukjinKwon/spark,dongjoon-hyun/spark,shaneknapp/spark,shaneknapp/spark,wangyum/spark,wangyum/spark,shaneknapp/spark,vinodkc/spark,wangyum/spark,mahak/spark,hvanhovell/spark,vinodkc/spark,srowen/spark,apache/spark,wangyum/spark,hvanhovell/spark,HyukjinKwon/spark,zzcclp/spark,ueshin/apache-spark,srowen/spark,HyukjinKwon/spark,dongjoon-hyun/spark,HyukjinKwon/spark