DOC: keep track of usage patterns, translate into useful instructions, add to docs

[jsheunis]

The idea is to keep track of how people are using metalad during the hackthon: Where are they looking for information? What type of info are they looking for? Do the docs need more comprehensive descriptions somewhere? Or perhaps a condensed version of a specific use case.

This issue can help track such new information as it comes to light, and it can then be iused to update the documentation accordingly.

[jsheunis]

• meta-conduct: https://github.com/datalad/datalad-metalad/issues/341
• Suggestions for improving performance when handling large amounts of metadata
• Explain the -r switch and meta-dump patterns clearly

[adswa]

Probably also pipelining