"docs(license): Add license file"

[ehealthafrica-ci]

Hi,

this in an automated script, I detected you don’t have a LICENSE file in your repo, so I added one with eHealth default license Apache-2.0. Please check if that is correct and merge accordingly.

In addition:

• If Apache-2.0 is the correct license, please check that there is no other (different) license mentioned anywhere in the repository. In particular check the README file or the package.json and bower.json files for Javascript projects.
• If you rejected this PR because Apache-2.0 is not the right license or no license is required, I’d appreciate it if you can add the reasons here. Also, if a license other than Apache-2.0 is used, don't forget to add a LICENSE file yourself!
• If you think this repository is obsolete and should be deleted, please add it here.