Naming of incubation process stages

[cornelius]

The current draft of the incubation process uses the terms (mostly inspired by the CNCF incubation process):

• Stage 0: Candidate
• Stage 1: Sandbox
• Stage 2: Incubation
• Stage 3: Graduated
• Stage 4: Retired

We noticed that in our context the terms "Sandbox" and "Incubation" are not easily understood and "Graduated" is also not always completely clear, so we should think about finding better terms.

Stage 1 (Sandbox) should express that these are new projects, which just entered the association and that work is going on to put them on a good quality level which is desired for most projects in the association.

Stage 2 (Incubation) is the stage for stable projects which have reached a satisfying quality level. Most projects will be in this stage for a long time. It's perfectly fine for a project to stay in this stage permanently.

Stage 3 (Graduated) is for the flagship projects of the association, which have found significant support by diverse contributors and wide adoption by users. These project are expected to meet very high quality standards.

[Keller-Peter]

I suggest:
0 Candidate
1 Approved
2 a. Developing
2 b. Productive
3 Mature (Community)
4 Retired

[cornelius]

We should revisit this at the latest when we have defined the criteria for all stages.