added JumpListMap implemenation, described data structure in readme

README.md

@@ -1,2 +1,19 @@
 # jumplists
-proof of concept implementation of a Map via median-of-k jumplists
+A proof-of-concept implementation of a SortedMap via median-of-k jumplists.
+
+Jumplists are a sorted singly-linked list that uses additional jump-pointer in elements
+to speed up searching in the list.
+This implementation is a randomized data structure that chooses the jump targets randomly.
+
+The methods get, put and remove all have expected logarithmic time complexity,
+where the expectation is w.r.t. the random structure of the jumplist.
+Jumplists also offer methods to select keys by rank, which also run in expected logarithmic time.
+The next method of iterators over the entries in sorted order has worst-case constant time complexity.
+A jumplist can be created in linear time from a list of sorted entries.
+
+Jumplists use three parameters:
+ * t1 and t2 control how the jump targets are chosen; t1 = t2 = 0 or t1 = t2 = 1 are advisable settings.
+   The larger these parameters, the more balanced the jumplist. 
+   This speeds up searches, but makes updates (insertions and deletions) more costly.
+ * w controls the maximal size of sublists for which no jump pointers are used; w = 100 seems advisable.
+   The larger w, the less storage is used, but searches become slower.