Text update for Local PV hostpath

[anupriya0703]

• The NodeAffinityLabel need to be removed from Create Storage Class sub-section and needs to be added as an advanced option.
• Review and test the page content.

Link- https://docs.openebs.io/docs/next/uglocalpv-hostpath.html

[anupriya0703]

• Removed the NodeAffinity parameter from Storage class creation YAML and added it as an optional section with a sample YAML with NodeAffinity parameter.