DevDocs: Add prerequisites to enable long paths in Windows (#41329)

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## Summary of the Pull Request
Added the "long paths" to the prerequisites in the DevDocs

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## PR Checklist
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [x] **Dev docs:** Added/updated

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## Detailed Description of the Pull Request / Additional comments
While setting up the PowerToys solution, I ran into repeated issues
where files or SDKs could not be found when loading the solution. After
a full evening of debugging, the root cause turned out to be Windows’
default path length limitation.

Even with a repository path like C:/Users/Micha/Development/PowerToys
(which is not unusually long by itself), the combination of folder
structure and file names exceeded the maximum allowed path length and
caused the build problems.

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Co-authored-by: Niels Laute <niels.laute@live.nl>

doc/devdocs/readme.md

@@ -76,6 +76,7 @@ Once you've discussed your proposed feature/fix/etc. with a team member, and an
 1. Windows 10 April 2018 Update (version 1803) or newer
 1. Visual Studio Community/Professional/Enterprise 2022 17.4 or newer
 1. A local clone of the PowerToys repository
+1. Enable long paths in Windows (see [Enable Long Paths](https://docs.microsoft.com/windows/win32/fileio/maximum-file-path-limitation#enabling-long-paths-in-windows-10-version-1607-and-later) for details)
 
 ### Install Visual Studio dependencies