Suggestions for implementation-notes.md

[pixelzoom]

Related to code review, https://github.com/phetsims/number-line-distance/issues/35

implementation-notes.md is generally very good. A few suggestions for improvements:

• [x] Use uppercase for screen and scene names, because that's how they are labeled. And you've used uppercase in model.md. E.g. "...the Explore screen..." versus "...the explore screen..."
• [x] Provide links to the .js files for sim-specific classes, so the reader can easily navigate to the code.
• [x] Property (uppercase) and property (lowercase) are totally different things. You are using the latter where you should be using the former.
• [x] Where "number line" is used as an adjective, it is a component adjective, and should be hyphenated. E.g. "The number line is..." vs "The number-line features are..."

[pixelzoom]

I made several of these improvements in the above commit, checked off in the checklist above. I'll leave it up to you to decide whether to add links to .js files.

[SaurabhTotey]

I added links, so I'll close this issue now.