Controller diagram

[hamishwillee]

Add position controller diagram from PX4/PX4-Autopilot#8316. You can see this rendered here.

@Stifael @bresch This is primarily for discussion. We might for example decide that:

• We want individual documents for each diagram
• We want a document for each controller, which happens to include the diagram.

Depends on what else is worth saying about controllers - e.g. What would you put in slides if you had to present on this in a webinar say :-) Links to source code etc?

@bresch there is also a placeholder doc for the notation. If you provide me the source text, I can add it (up to you).

[hamishwillee]

@bresch You may be on holiday, but if not, can you send me your notation doc? I'd rather get this merged and then iterate than wait on perfection.

@Stifael Any thoughts on discussion in #400 (comment) . Specifically, what else would you like said here or is it OK? Is there a lot more that we might say in a position controller document such that this would just be part of that document?

[bresch]

can you send me your notation doc?

The glossary? Here is its repo