Rewrite readmes

[jsoref]

Description

Fix various grammatical elements in the readmes

Motivation and Context

The content needed an editor to review it.

How Has This Been Tested?

• I checked a number of the links (a couple were broken).
• I fed some of the content to app.grammarly.com

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (add or update README or docs)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[lvpx]

Excellent effort on fixing these @jsoref 💯

[bishal-pdMSFT]

Technically a key does not identify a cache uniquely which I feel this sentence seems to be indicating. Hence better to go back to older text.

Suggested change

	* `key` - An explicit key identifying a cache. See [creating a cache key](#creating-a-cache-key).
	* `key` - An explicit key for restoring and saving the cache. See [creating a cache key](#creating-a-cache-key).

[jsoref]

Would you accept naming instead of identifying?

I'm trying to:

• avoid the awkwardness of restoring and saving instead of saving and restoring -- yes, I get that the sequence is restore and then save (although I believe that in practice it will really only restore or save, because if the cache exists to restore, it will not save since caches are write-once by id)
• harmonize the text across all three files

[jsoref]

I've applied this change:

-* `key` - An explicit key identifying a cache. See [creating a cache key](../README.md#creating-a-cache-key).
+* `key` - An explicit key for a cache entry. See [creating a cache key](../README.md#creating-a-cache-key).

Which seems like a more correct entry. It's consistent with the wording in nearby lines, avoids the problem of the restore/save, and avoids using the awkward identifying.

[bishal-pdMSFT]

This file itself is for examples. Do we really this?

[jsoref]

This file section an attractive nuisance. I'm pretty sure that VSCode did this on its own.

[bishal-pdMSFT]

The content needed an editor to review it.

So true :)

Thanks @jsoref for opening this PR and making really good suggestions. I have left a couple comments.

[jsoref]

@bishal-pdMSFT: if you're ok w/ the one swap to naming, I'll rebase w/ that change -- (and try to drop the ToC mess...)

[kotewar]

Looks good to me, thanks for the PR! 👍🏽