Simplify conda readme
Simplify conda readme

* Remove PYTHONHASHSEED hack, as the relevant Spark bug has been fixed
    in Dataproc 1.2 (the new default image)
* Make first usage example clearer
* Fix conda env path

lukeFalsina/dataproc-initialization-actions,GoogleCloudDataproc/initialization-actions,dennishuo/dataproc-initialization-actions,pmkc/dataproc-initialization-actions,dennishuo/dataproc-initialization-actions,lukeFalsina/dataproc-initialization-actions,GoogleCloudDataproc/initialization-actions,pmkc/dataproc-initialization-actions,GoogleCloudDataproc/initialization-actions