[Maintenance] Add acceptable milestones and proper label filters

[xames3]

• this is a trivial issue with fewer key deliverables:

  • setup appropriate labels for issues and pull requests. we can follow a similar strategy for the repository labels mentioned on the CreativeCommons site here. although, we don't need to comply totally to their schema (<emoji>⎵<category>:⎵<name>) but can use it as a baseline for relevant flows.
  • although, this is not as significant as the other task, but we need to setup milestones for the project. as of now, no details about milestones are found pertaining to open-source and open-science, which does seem appropriate for our project. need to discuss this internally in the next meeting or maybe ask the @ciesin-geospatial core development team for this information.

[xames3]

• labels have already been added to the project. the @ciesin-geospatial team needs to decide on the deliverable milestones for the repository. can be moved to in progress.