docs: clarify that center layout height controls results window, not full layout

[aryanexe07]

Description

Clarifies the behavior of height in the center layout strategy.
The previous wording ("How tall to make Telescope's entire layout") was
misleading — in the center layout, height controls the results window
height, not the full layout. Setting it too high can shrink or obscure
the preview window.

Also reverts an incorrect edit to the horizontal layout section.

Fixes #3623

Type of change

• This change requires a documentation update

How Has This Been Tested?

N/A — documentation-only change. The height description was updated in
the lua annotations, which auto-generates telescope.txt via make docgen.

• Test A
• Test B

Configuration:
N/A

Checklist:

• My code follows the style guidelines of this project (stylua)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (lua annotations)

[aryanexe07]

The telescope.txt file is auto-generated via make docgen.
I've updated the lua annotation in layout_strategies.lua to override
the height description specifically for the center layout using
vim.tbl_extend("force", ...) instead of "error", so other layouts
are unaffected. The telescope.txt changes reflect what make docgen
produces from that annotation change.

[aryanexe07]

Thanks, Happy to make any changes if the wording or
approach needs adjustment.

[Conni2461]

thanks :)

[aryanexe07]

welcome, thank you letting me work on this, i appreciated