Change wording of "Focus mode"

[mecattaf]

One of the features of v1.0.0 release:
"IDEA: Focus mode, where the focused application appears up front and center"

Please use a different term as "Focused Window" or focus is a key part of sway and i3wm:

<criteria> focus

Moves focus to the container that matches the specified criteria.
focus up|right|down|left

Moves focus to the next container in the specified direction.
focus prev|next [sibling]

Moves focus to the previous or next container in the current layout. By default, the last active child of the newly focused container will be focused. The sibling option indicates not to immediately focus a child of the container.
focus child

Moves focus to the last-focused child of the focused container.
focus parent

Moves focus to the parent of the focused container.
focus output up|right|down|left

Moves focus to the next output in the specified direction.
focus output <name>

Moves focus to the named output.
focus tiling

Sets focus to the last focused tiling container.
focus floating

Sets focus to the last focused floating container.
focus mode_toggle

Moves focus between the floating and tiled layers.

[sudopluto]

centerstage? active? selected? upfront?