docs: npm install upper version limit (#61)

Author: stepansergeevitch

README.md

@@ -7,7 +7,7 @@
 This library is published in the NPM registry and can be installed using any compatible package manager.
 
 ```sh
-npm install firebolt-sdk --save
+npm install firebolt-sdk@0.X --save
 
 # For Yarn, use the command below.
 yarn add firebolt-sdk