Update Leaflet documentation (2.0.0-alpha1)

Author: simon04

lib/docs/scrapers/leaflet.rb

@@ -20,7 +20,7 @@ class Leaflet < UrlScraper
     HTML
 
     version '2.0' do
-      self.release = '2.0.0-alpha'
+      self.release = '2.0.0-alpha1'
       self.base_url = "https://leafletjs.com/reference-2.0.0.html"
     end