LASCO C2 data sampled needed for example gallery

[Hermanlrx]

Describe the feature

I have been working on adding a LASCO C2 sample for the example gallery with the following issues in mind:

• Add some coronagraph sample data sunpy#5471
• Make sure example gallery is using the smallest possible set of data sunpy#5632
• Add coronagraph composite-type plot to gallery (e.g. AIA, LASCO C2, C2 sunpy#6420

Adding the file seems to be first step before trying to change: _sample.py

and the related docs.

An AIA/LASCO C2 overlaying example on the docs is failing for an unrelated reason (helioviewer api unreachable). This example can be updated if the file is added as part of the data collection (should a different issue be made for this?):
Lasco overlay

Proposed solution

#49

No response