Improve the documentation for emberAfFindClusterServerEndpointIndex.

[bzbarsky-apple]

No description provided.

[github-actions]

PR #25985: Size comparison from e4faf94 to 4193b5f

Increases (1 build for cc32xx)

platform	target	config	section	e4faf94	4193b5f	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL	.debug_abbrev	933099	933119	20	0.0
			.debug_info	20302987	20302990	3	0.0
			.debug_line	2679748	2679759	11	0.0

Full report (1 build for cc32xx)

platform	target	config	section	e4faf94	4193b5f	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL		0	0	0	0.0
			(read only)	642745	642745	0	0.0
			(read/write)	203848	203848	0	0.0
			.ARM.attributes	44	44	0	0.0
			.ARM.exidx	8	8	0	0.0
			.bss	197248	197248	0	0.0
			.comment	194	194	0	0.0
			.data	1480	1480	0	0.0
			.debug_abbrev	933099	933119	20	0.0
			.debug_aranges	87608	87608	0	0.0
			.debug_frame	301328	301328	0	0.0
			.debug_info	20302987	20302990	3	0.0
			.debug_line	2679748	2679759	11	0.0
			.debug_loc	2824679	2824679	0	0.0
			.debug_ranges	286200	286200	0	0.0
			.debug_str	3039406	3039406	0	0.0
			.ramVecs	780	780	0	0.0
			.resetVecs	64	64	0	0.0
			.rodata	104289	104289	0	0.0
			.shstrtab	232	232	0	0.0
			.stab	204	204	0	0.0
			.stabstr	441	441	0	0.0
			.stack	2048	2048	0	0.0
			.strtab	377422	377422	0	0.0
			.symtab	256768	256768	0	0.0
			.text	536336	536336	0	0.0