This is an attempt to clean up the inconsistent way that keys are
written in various places. These rules require the fewest changes to the
existing text.
Use the "Key name", as defined in remapping.md, which uses
"Some-Modifiers-PascalCaseKey". The "Representation", which uses
"S-M-lowercasekey", is only used for configuration entries.
For key combinations which do not present a popup, just present the keys
one after the other, with no intervening space, like `]p`.
For key combinations which present a popup, separate them with ` + `,
like `Space + f`.
The Ctrl modifier is called Ctrl, not Control.