Add Example for Regular Lat-Lon Grid

[sfinkens]

After introducing a couple of students/interns to pyresample I found that it would be useful to have an example explaining how to get the area definition for a given regular lat-lon grid.

I also separated the area definition examples into separate code blocks to improve the readability.

• Tests passed
• Passes git diff origin/master **/*py | flake8 --diff

[djhoese]

Technically eqc is not a "lat/lon" grid, right? It is in meters. A lat/lon grid would be +proj=latlong.

[sfinkens]

Yes, good point. Changed it to latlong.

[sfinkens]

Hm, but now the example doesn't fit the "...even if the projection space is defined in meters" anymore. I'll just add an extra sentence for that.

[mraspaud]

LGTM

[codecov]

Codecov Report

Merging #204 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #204   +/-   ##
=======================================
  Coverage   87.22%   87.22%           
=======================================
  Files          39       39           
  Lines        7161     7161           
=======================================
  Hits         6246     6246           
  Misses        915      915

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[coveralls]

Coverage remained the same at 87.195% when pulling 21185ca on sfinkens:doc-geometry-utils into 9be0871 on pytroll:master.