Corrections to the mage.exe page

[BartoszKlonowski]

This pull request fixes #35326
It makes necessary corrections to the mage.exe page such as:

• removing the misleading statement regarding the -a option with -Sign
• adding the other now supported options to the -Sign command
  Those newly added are -TimestampUri and -Algorithm. They are mostly copy-paste from the general table, however, I removed "Use with -update option" statement from Algorithm, since I couldn't see that requirement when applying in -Sign context.

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Internal previews

📄 File	🔗 Preview link
docs/framework/tools/mage-exe-manifest-generation-and-editing-tool.md	Mage.exe (Manifest Generation and Editing Tool)

[gewarren]

Thanks @BartoszKlonowski

[gewarren]

#35326 states only one algorithm is valid for -Sign.