- New section at top: 'Getting started with ffmpeg'. Added basic command explanation under this heading.
- New section at bottom: 'Advanced ffmpeg concepts'. Filtergraph explanation moved there.
- Move 'Set stream properties' to the 'Change video properties' section.
- Heading change: 'Create a video' to 'Create a video from images'. (In the ToC, it's 'Create a video from image(s) and audio')
- 'View Subprogram Info' is fixed (data-target now matches the new ID).
- Consistent capitalisation
These links wrap a <button> tag and use the "btn" class. To distinguish them from the command buttons that trigger the modals, I've given them a different colour scheme and a different emoji prefix.
'View format info' seemed to me to be poorly named, what this command actually does is to give details of various libraries, muxers, encoders, etc. 'View ffmpeg subprogram info' may not itself be a totally correct nomenclature, but it's a bit closer to the practical meaning, I think.
Also: a couple of minor text changes.
In several places, ffprobe or ffplay commands said ffmpeg in the command breakdown. This is because of me doing a sloppy cut & paste in a previous commit in this PR.
Previously, colons succeeding a bold 'Notes' mini-heading were not themselves also bold. Reto noted this, and the Chicago Manual of Style does indicate that such colons should also be in bold.
In filtergraphs that are reasonably long or unwieldy, I've added a space after each comma for readability.
In ffmpeg commands, italics should denote user inputs/outputs. Where italics had been used for 'regular' variables (i.e., not an input/output file or a variable for which the user must explicitly choose the value), I've deleted them.
These are stylistic changes that, I think, make things more readable and/or more uniform.
I've elaborated further on certain commands, and added lines for opening and closing quotation marks for others.
There are also some minor style fixes.
