Merge pull request #2192 from C3pa/string-find-update

Mark string.find return values as nilable

Author: sumneko

meta/template/string.lua

@@ -31,9 +31,9 @@ function string.dump(f, strip) end
 ---@param pattern string|number
 ---@param init?   integer
 ---@param plain?  boolean
----@return integer start
----@return integer end
----@return any ... captured
+---@return integer|nil start
+---@return integer|nil end
+---@return any|nil ... captured
 ---@nodiscard
 function string.find(s, pattern, init, plain) end