docs(lua): move function docs to lua files

runtime/lua/vim/_meta/spell.lua

@@ -0,0 +1,29 @@
+--- @meta
+
+--- Check {str} for spelling errors. Similar to the Vimscript function
+--- |spellbadword()|.
+---
+--- Note: The behaviour of this function is dependent on: 'spelllang',
+--- 'spellfile', 'spellcapcheck' and 'spelloptions' which can all be local to
+--- the buffer. Consider calling this with |nvim_buf_call()|.
+---
+--- Example:
+--- <pre>lua
+---     vim.spell.check("the quik brown fox")
+---     -- =>
+---     -- {
+---     --     {'quik', 'bad', 5}
+---     -- }
+--- </pre>
+---
+--- @param str string
+--- @return {[1]: string, [2]: string, [3]: string}[]
+---   List of tuples with three items:
+---     - The badly spelled word.
+---     - The type of the spelling error:
+---         "bad"   spelling mistake
+---         "rare"  rare word
+---         "local" word only valid in another region
+---         "caps"  word should start with Capital
+---     - The position in {str} where the word begins.
+function vim.spell.check(str) end