docs(api): correct type signature

doc/rocks.txt

@@ -183,7 +183,7 @@ api.try_get_cached_outdated_rocks()          *api.try_get_cached_outdated_rocks*
     if it is not ready.
 
     Returns: ~
-        (table<rock_name,OutdatedRock[]>)  rocks
+        (table<rock_name,OutdatedRock>)  rocks
 
 
 api.query_luarocks_rocks({callback})                  *api.query_luarocks_rocks*

lua/rocks/api/init.lua

@@ -53,7 +53,7 @@ end
 ---or no connection to luarocks.org can be established.
 ---Will spawn an async task to attempt to populate the cache
 ---if it is not ready.
----@return table<rock_name, OutdatedRock[]> rocks
+---@return table<rock_name, OutdatedRock> rocks
 function api.try_get_cached_outdated_rocks()
     return cache.try_get_outdated_rocks()
 end

lua/rocks/cache.lua

@@ -32,7 +32,7 @@ local _cached_dev_binaries = nil
 ---@type string[] | nil
 local _removable_rock_cache = nil
 
----@type table<rock_name, OutdatedRock[]> | nil
+---@type table<rock_name, OutdatedRock> | nil
 local _outdated_rock_cache = nil
 
 ---Tries to get the cached value
@@ -117,7 +117,7 @@ end)
 ---Tries to get the cached removable rocks.
 ---Returns an empty list if the cache is not ready,
 ---and triggers an async task to populate the cache.
----@return table<string, Rock[]> rocks indexed by name
+---@return table<string, OutdatedRock> rocks indexed by name
 function cache.try_get_outdated_rocks()
     return try_get_unsafe(_outdated_rock_cache, cache.populate_outdated_rock_cache)
 end