Rearrange Documentation Folder

[noursaidi]

Builds on PR #196 to rearrange the documentation folders.

readme's for the new directories to come in a future update, as will documentation for the new items in the list

Comments on the PR were incorporated. Additional changes were also:

• Renamed messages to messaging like status, pointset aren't messages but are part of the messages; and we also have the schema)
• Moved metadata out of the messages directory
• Renamed dashboard to cloud
• Renamed config writeback to writeback
• Renamed implementation guide to guides

[grafnu]

Overall looks good, thanks. I think a few top-level names are inconsistent and should be munged just a bit:

specification --> specs
messaging--> messages
transactions --> sequences (nothing inherently wrong with transactions, but the testing code currently calls them sequences so trying to be consistent)
cloud --> clouds/gcp

Also, I wouldn't put "messages" under "specification" -- I think messages is significant enough to be its own top level entry.

I'm not sure the "applications" hierarchy is useful... there are tools (e.g. pubber.md) and then cloud stuff (clouds/gcp) -- but the cloud stuff isn't really tools, it's a complete ecosystem.