Merge !996

Add summary to blog post

See merge request monero-project/monero-site!996

_posts/2019-02-01-pruning.md

 ---
 layout: post
 title: Monero Adds Blockchain Pruning and Improves Transaction Efficiency
-summary: 
+summary: Monero adds pruning and reduces range proof verification time with forthcoming upgrade
 tags: [dev, core, crypto]
 author: [Justin Ehrenhofer](https://twitter.com/JEhrenhofer)
 ---