Since this is a small doc I did it in one go. Hope that's OK.
General polish to the text and simplification where possible. Used "RS-274X" since that's the exact nomenclature used in the Gerber standard. Removed explicit references to Pcbnew's output, since GerbView can view files from most any PCB design tool. Made all toolbar icon descriptions verb-noun. Fixed table so the last left toolbar icon isn't hidden. Removed subjective or unhelpful text like "Previously (a long time ago) it was also possible to load so called Dcodes, but those are now obsolete and is therefore not possible anymore.". Pushed the printing section to the end so that moving items is already described.
NOTE: As I moved the display modes into new sections ("==="), the images disappeared; reverting this change didn't fix it. I'll take a look at this more later, but I'm submitting this patch for review since I think everything might be OK and the issue is GitHub trying to render the differences.
* Batch of fixes for PR #397
Changed title of UI section to Interface and moved Layers Manager section here. Removed icons from inline with section headers. Added page breaks above large tables.
I used "some" computers in the Display modes section rather than "older" computers drivers or another issue the documentation may not want to specify could be at fault. Is this OK?
