10). Add topic files 15 to 18

[jameshkramer]

@mairaw
This PR is for user story #1576037.

It adds four topic files, makes corresponding deletions from the C# and VB folders, and adds redirection entries. There are also minor fixes to a few other files.

cc: @tfosmark

Contributes to #4728

[BillWagner]

Thanks @jameshkramer I gave this a good review today. A few comments:

First, there are a number of warnings for the additions in the new TOC in the standard folder.
Second, and possibly @mairaw can provide more insight here. What's the reason behind not removing nodes from the articles that are moving and consolidating?

Otherwise, it looks great.

[mairaw]

I'll try to get this reviewed later today. I think we can have a separate PR that removes the entire nodes from the previous locations. We usually have some warnings happening until all articles are merged but I believe this one has some extra ones that need to be dealt with before merging.

[pkulikov]

@mairaw this PR is not intended for the master and should be retargered?

[jameshkramer]

@pkulikov, yes, sorry, the target should be linq-to-xml, not master, and I have now corrected it. I wonder when I will stop making this mistake.

cc: @mairaw, @BillWagner

[jameshkramer]

@BillWagner @mairaw

Bill, thanks for reviewing these. I'm glad you find them suitable. Maira, I appreciate you're taking a look also.

I'll look at the redirection warnings.

I plan three more PRs this week, with 12 more articles.

[jameshkramer]

Apparently the great majority of the warnings are for "file not found", because the TOC refers to files that haven't been merged yet. These will be fixed over time. However the first four are "redirection url found conflict", and the message says "appears twice or more in the redirection mappings". It seems these result from there being redirections to the merged file in /standard from both the C# and the VB versions. Do we need to do something here, or just ignore the messages?

[mairaw]

Some of the warnings will still have to be corrected like
"The '/dotnet/standard/linq/catch-parsing-errors' appears twice or more in the redirection mappings"

[jameshkramer]

But what is the fix? I thought we wanted both the C# and the VB versions to be redirected to the merged version.

[mairaw]

Thanks @jameshkramer!