Remove max_item_count from source configuration

doc/cmp.txt

@@ -570,11 +570,6 @@ sources[n].priority~
   `number`
   The source-specific priority value.
 
-                                          *cmp-config.sources[n].max_item_count*
-sources[n].max_item_count~
-  `number`
-  The source-specific item count.
-
                                              *cmp-config.sources[n].group_index*
 sources[n].group_index~
   `number`

lua/cmp/types/cmp.lua

@@ -158,7 +158,6 @@ cmp.ItemField = {
 ---@field public trigger_characters string[]|nil
 ---@field public keyword_pattern string|nil
 ---@field public keyword_length integer|nil
----@field public max_item_count integer|nil
 ---@field public group_index integer|nil
 ---@field public entry_filter nil|function(entry: cmp.Entry, ctx: cmp.Context): boolean