Enhance entries where two options are described

[daobrien]

We often say (e.g.) "Use the one-word form" but it doesn't help if people look up the two-word or hyphenated form and it's not there. It just makes it harder and slower to find things.

• [ ] ⁠data center (n.) Use the two-word form... It would be better if this included "Do not use 'datacenter' or 'data-center'" or something similar.
• [ ] ⁠data source (n.)
• [x] 3-D