Update the "Variable Descriptions" guidance text

[pripley123]

As a operational maintainer of OCWA,

I want to make the Variable Descriptions field guidance text clearer

so that I can better communicate to requester what information is desired to be entered in this field.

Test Case

ENV

• DEV
• TEST
• PROD

TESTCASE

When requester goes to the "New Request" page
Then the "Variable Descriptions" guidance text should say:

"Provide the variable/field names of the original and self-constructed variables. For original variables please use the name from the metadata."

[Jonesy]

Fixed in #142