Edit the lispref manual for define-key/keymap-set fallout

Edit the lispref manual for define-key/keymap-set fallout

* doc/lispref/variables.texi (Tips for Defining):
* doc/lispref/text.texi (Clickable Text):
* doc/lispref/modes.texi (Derived Modes):
(Example Major Modes):
* doc/lispref/loading.texi (Autoload):
(Hooks for Loading):
* doc/lispref/keymaps.texi (Creating Keymaps):
(Inheritance and Keymaps):
(Controlling Active Maps):
(Changing Key Bindings):
(Low-Level Key Binding):
(Remapping Commands):
(Translation Keymaps):
(Key Binding Commands):
* doc/lispref/help.texi (Help Functions):
* doc/lispref/display.texi (Abstract Display Example):
* doc/lispref/commands.texi (Interactive Codes):
(Keyboard Events):
(Misc Events):
(Classifying Events):
(Strings of Events): Prefer `keymap-set' instead of `define-key'
most places, and use `defvar-keymap' in some of the examples.