Community survey post

Here it is - the long overdue community part of the HIFIS Survey blog post series.

@mdolling-gfz: Feel free to rewrite any part that is too sciency or too boring
@frere76 or @erxleb87: It would be great if one of you could check for language errors or improvements
@SpickerHZB: After yesterday's survey meeting, I am not quite sure whether the left part of the first figure (survey responses per center) already is too "emotional". Showing which centers we reached with the survey is not meant as some sort of evaluation but after what we discussed yesterday I just want to make sure that this is not problematic in some sense.

Feedback is greatly appreciated. Thanks :)