INI migration guide (CnCNet#483)

* Add second migration guide

* Update Migration-INI.md

* Add mention in the main migration guide

* Update Migration-INI.md

* Add extra empty lines between headers and code blocks

* Reference a specific mod base commit, revert .NET 7 changes

* Make large code blocks collapsible, add more descriptions

* Refer to the new version as 2.11.0.0

* Mention .NET 8 binaries again

* Reorder paragraphs

* Enforce 80 character line width

* Don't use the word "root" when referring to the game directory root

* Make .NET 8 build not optional

* Mention the second stage updater

* Stash

* Ensure that the migration guide works

* Add directory tree view  for executables

* Remove hard line wrap

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Co-Authored-By: SadPencil <sadpencil@outlook.com>