refactor: constructors, update docs

- NewCustomTable -> NewCustom
- NewTableBy -> NewBy
- NewTable -> New

doc.go

@@ -1,8 +1,8 @@
 // Package cuckoo provides a hash table that uses cuckoo hashing to achieve
 // a worst-case O(1) lookup time.
 //
-// While a [NewTable] only supports comparable keys by default, you can create
-// a table with any key type using [NewCustomTable]. Custom [Hash] functions and
+// While a [New] only supports comparable keys by default, you can create
+// a table with any key type using [NewCustom]. Custom [Hash] functions and
 // key comparison are also supported.
 //
 // See more: https://en.wikipedia.org/wiki/Cuckoo_hashing