Updated Readme so that the option to keep persistency can be found

Author: Albert Alonso

README.md

@@ -251,6 +251,8 @@ optimizer.maximize(
 )
 ```
 
+By default the previous data in the json file is removed. If you want to keep working with the same logger, the `reset` paremeter in `JSONLogger` should be set to False.
+
 ### 4.2 Loading progress
 
 Naturally, if you stored progress you will be able to load that onto a new instance of `BayesianOptimization`. The easiest way to do it is by invoking the `load_logs` function, from the `util` submodule.
@@ -324,4 +326,4 @@ If you used this package in your research and is interested in citing it here's
 * http://papers.nips.cc/paper/4522-practical-bayesian-optimization-of-machine-learning-algorithms.pdf
 * http://arxiv.org/pdf/1012.2599v1.pdf
 * http://www.gaussianprocess.org/gpml/
-* https://www.youtube.com/watch?v=vz3D36VXefI&index=10&list=PLE6Wd9FR--EdyJ5lbFl8UuGjecvVw66F6
+* https://www.youtube.com/watch?v=vz3D36VXefI&index=10&list=PLE6Wd9FR--EdyJ5lbFl8UuGjecvVw66F6