Revise signature of raxSeek in the README

Author: fxn

README.md

@@ -180,7 +180,7 @@ of 'seek', which is not 'seeked', in case you wonder) in order to start
 the iteration from the specified position. For this goal, the function
 `raxSeek` is used:
 
-    int raxSeek(raxIterator *it, unsigned char *ele, size_t len, const char *op);
+    int raxSeek(raxIterator *it, const char *op, unsigned char *ele, size_t len);
 
 For instance one may want to seek the first element greater or equal to the
 key `"foo"`: