Allow conan new templates to contain Readme.md and LICENSE.txt files

[stefansli]

This is just a small fix. I didn't find an issue for this and I don't think an issue is needed. I'm not sure if changes to the documentation are needed. On one hand the docs are clear that Readme.md and LICENSE.txt are skipped, on the other hand for templates these kinds of files are sometimes essential.

Changelog: Fix: Allow templates for conan new to contain Readme.md and LICENSE.txt files.
Docs: omit

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[memsharded]

Hi @vectorsli

Thanks for contributing this fix.
This has already been fixed in 2.0, indeed that didn't make sense.
Could you please add a very short test, or maybe it is enough to add a README file in some of the existing tests, to validate this is working fine?

[memsharded]

Merged without a test, but the risk is very low.