[#2] Add .asf.yaml to add repo description

[kaxil]

closes #2

[mik-laj]

Can you aim with your change to the branch that contains the source code instead of the generated files? https://github.com/apache/airflow-site/tree/aip-11/landing-pages/site/static
Otherwise your change will be overwritten the next time the website is updated.
aip-11 is the current development branch for the project.
master is the working branch where the source code will be after accepting the final code.
#174
asf-site contains generated files and should not be modified directly. In the future it will be generated based on CI / CD.

[kaxil]

@mik-laj I have created a new PR for aip-11 branch: #216

[ashb]

Oh man, I didn't know asf would automatically publish from pelican for us https://cwiki.apache.org/confluence/display/INFRA/.asf.yaml+features+for+git+repositories#id-.asf.yamlfeaturesforgitrepositories-CMS/pelicansub-directoriesforstaticoutput - if I'd known that I would have asked that we wrote the site in Pelican not Hugo.