Port System.Linq.Expressions source comments to Docs

[carlossanlop]

Summary

Automatically porting a few triple slash source code comments found in System.Linq.Expressions that were not yet documented in dotnet-api-docs.

Fixes #Issue_Number (if available)

[carlossanlop]

@mairaw @rpetrusha please take a look whenever possible.

Adding the area owners @cston, @333fred. Charles, Fred, can you please take a look? The summary messages I ported are all generic and have exactly the same string, so it would be awesome if the code experts could jump in to edit them into some more descriptive and specific summaries.

[333fred]

Assuming that I'm reading the XML correctly and this adds docs to a bunch of Accept methods, these look fine to me.

[carlossanlop]

@mairaw @rpetrusha if this looks good enough, can we get it merged?

[rpetrusha]

The summaries look good, @carlossanlop, but the parameter descriptions and return values are missing. Would it be possible for you to also add those? The parameter description is, "The visitor to visit this node with." The return value description is "The result of visiting this node."

[carlossanlop]

The summaries look good, @carlossanlop, but the parameter descriptions and return values are missing. Would it be possible for you to also add those? The parameter description is, "The visitor to visit this node with." The return value description is "The result of visiting this node."

For the visitor parameter, would it sound better to use the following instead?:

"The <see cref="T:System.Linq.Expressions.ExpressionVisitor"> with which this node will be visited."

[carlossanlop]

@rpetrusha done.

[rpetrusha]

Thanks for making all of the additional changes, @carlossanlop. I'll merge your PR now.

[carlossanlop]

Thank you @rpetrusha !