[DOC]: Revert official project name from "XCDAT" to "xCDAT"

[tomvothecoder]

Describe your documentation update

Reasons to use "xCDAT":

• It sounds like it xarray + CDAT capabilities
• Some folks have already been referring to this project as "xCDAT"
• Names of xarray related packages seem to usually start with a lower case "x" (e.g., "xEMSF")

Reasons to use "XCDAT"

• Grammatically incorrect since it is technically an acronym
• Might be less readable to some

Next Steps

We are leaning towards "xCDAT".

• Official project name: "xCDAT" (not strict if users use "XCDAT")
• Python package name: "xcdat"
• Update "xCDAT" logo with smaller "x"

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Related xarray issue related to its name: pydata/xarray#1306

“Yes, this is a little silly, but do we have a preferred capitalization for the proper name?

We mostly stick to ‘xarray’ in the docs but ‘Xarray’ or ‘XArray’ is arguably a little more readable and grammatically correct.”

“I like xarray because it is the same as the python package. However, for aesthetic reasons I capitalize Xarray when used for titles or at the beginning of a sentence...”

“Closing this. We use "xarray" in the middle of sentences and "Xarray" at the start but aren't that strict about it.

Yes: Xarray (at start of sentences), xarray (in middle)
No: XArray, xArray”