Clean up typos in Activity.cs

[v-kydela]

I noticed some typos in the documentation comments in Activity.cs, so I fixed them. They largely appear to have been caused by copying and pasting.

[coveralls]

Pull Request Test Coverage Report for Build 46089

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 55.792%

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Totals
Change from base Build 45824:	0.0%
Covered Lines:	5500
Relevant Lines:	9858

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 46631

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 16 unchanged lines in 1 file lost coverage.
• Overall coverage remained the same at 55.792%

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Files with Coverage Reduction	New Missed Lines	%
/libraries/Microsoft.Bot.Builder.Dialogs/DialogContext.cs	16	69.72%

Totals
Change from base Build 45824:	0.0%
Covered Lines:	5500
Relevant Lines:	9858

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💛 - Coveralls

[cleemullins]

Thanks Kyle. This is great.

However... (there's always a however)

Can you remove the Activity.cs changes from this PR? That class is auto-generated from Swagger and your changes will be wiped out the next time the class is generated. The changes in the other classes ComponentDialog, DialogSet, etc, are all things we should take ASAP.

To "Fix" the Activity.cs means changing the server side code that generates the swagger file via Swashbuckle. If you are up for doing that, talk to Craig or Artur who can point you in the right direction.

[v-kydela]

Thank you, Chris. I would like to submit a new pull request for the sake of cleanliness. I do not want to risk corrupting the repository with rebases, etc. This pull request can be rejected.

[v-kydela]

Never mind the new pull request idea. I've just added a new commit that reverts the Activity.cs commit