Add docs for keyboard shortcuts.

[junhaoliao]

Request

We have keyboard shortcuts configured for the Monaco editor:

yscope-log-viewer/src/utils/actions.ts

Lines 27 to 63 in 939d4ac

	const EDITOR_ACTIONS : EditorAction[] = [
	{
	actionName: null,
	label: "Focus on Editor",
	keyBindings: [monaco.KeyCode.Backquote],
	},
	{
	actionName: ACTION_NAME.FIRST_PAGE,
	label: "First page",
	keyBindings: [monaco.KeyMod.CtrlCmd | monaco.KeyMod.Shift | monaco.KeyCode.BracketLeft],
	},
	{
	actionName: ACTION_NAME.PREV_PAGE,
	label: "Previous page",
	keyBindings: [monaco.KeyMod.CtrlCmd | monaco.KeyCode.BracketLeft],
	},
	{
	actionName: ACTION_NAME.NEXT_PAGE,
	label: "Next page",
	keyBindings: [monaco.KeyMod.CtrlCmd | monaco.KeyCode.BracketRight],
	},
	{
	actionName: ACTION_NAME.LAST_PAGE,
	label: "Last page",
	keyBindings: [monaco.KeyMod.CtrlCmd | monaco.KeyMod.Shift | monaco.KeyCode.BracketRight],
	},
	{
	actionName: ACTION_NAME.PAGE_TOP,
	label: "Top of page",
	keyBindings: [monaco.KeyMod.CtrlCmd | monaco.KeyCode.KeyU],
	},
	{
	actionName: ACTION_NAME.PAGE_BOTTOM,
	label: "Bottom of page",
	keyBindings: [monaco.KeyMod.CtrlCmd | monaco.KeyCode.KeyI],
	},
	];

but there's no user guide / help menu explaining what are available in the new log viewer.

Possible implementation

We can either add a helper menu, or document the shortcuts in the user guide.