Rename license.md to LICENSE

[yvan-sraka]

Following GitHub guidelines

• [x] Try to keep the pull requests small; a pull request should try its very best to address only a single concern.
• [x] Make sure all tests pass and add additional tests for the code you submit.
• [x] Document your reasoning behind the changes. Explain why you wrote the code in the way you did; the code should explain what it does.
• [x] If there's an existing issue related to the pull request, reference to it by adding Fix #305, where 305 is the issue number.

Short description of what this resolves:

• License isn’t show in the project header description on GitHub

Changes proposed in this pull request:

• Rename license.md file to LICENSE

[dhoko]

Thx 👍