[dev] fix readme description, add lock files

Author: AlexKlimenkov

.gitignore

@@ -18,4 +18,4 @@
 npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
-yarn.lock
+package-lock.json

README.md

@@ -1,6 +1,6 @@
 <h1 align="center"><a href="https://docs.dhtmlx.com/scheduler/">DHTMLX Scheduler Documentation</a></h1>
 
-New Scheduler description here
+DHTMLX Scheduler is a JavaScript library for developing scheduling applications.
 
 ## Explore documentation locally