Please update CRW 1.2 / OSD 4 Instructions to reference needed namespace

CRW did not allow installation on OpenShift Dedicated until recently, because the Operator was not available.
Thanks to SREP-2230 [1], this is no longer true. The Operator is available and is known to work. There is a limitation, though.

Per SREP-2245 [2], the following restrictions exist:

• Installation should target the namespace `openshift-codeready-workspaces` for both the Operator and the Custom Resource 'CheCluster'.

Please update the CRW doc to reflect these restrictions.

[1] https://jira.coreos.com/browse/SREP-2230
[2] https://jira.coreos.com/browse/SREP-2245