Update README.md

Author: 2017pxy

README.md

@@ -23,7 +23,7 @@
 
 RecBole is developed based on Python and PyTorch for reproducing and developing recommendation algorithms in a unified,
 comprehensive and efficient framework for research purpose.
-Our library includes 77 recommendation algorithms, covering four major categories:
+Our library includes 78 recommendation algorithms, covering four major categories:
 
 + General Recommendation
 + Sequential Recommendation