Erlang: Added begin keyword (#3387)

Author: hoonweiting

components/prism-erlang.js

@@ -13,7 +13,7 @@ Prism.languages.erlang = {
 		alias: 'atom'
 	},
 	'boolean': /\b(?:false|true)\b/,
-	'keyword': /\b(?:after|case|catch|end|fun|if|of|receive|try|when)\b/,
+	'keyword': /\b(?:after|begin|case|catch|end|fun|if|of|receive|try|when)\b/,
 	'number': [
 		/\$\\?./,
 		/\b\d+#[a-z0-9]+/i,

components/prism-erlang.min.js

@@ -1,15 +1,15 @@
 fun when case of
-end if receive
+begin end if receive
 after try catch
 
 ----------------------------------------------------
 
 [
 	["keyword", "fun"], ["keyword", "when"], ["keyword", "case"], ["keyword", "of"],
-	["keyword", "end"], ["keyword", "if"], ["keyword", "receive"],
+	["keyword", "begin"], ["keyword", "end"], ["keyword", "if"], ["keyword", "receive"],
 	["keyword", "after"], ["keyword", "try"], ["keyword", "catch"]
 ]
 
 ----------------------------------------------------
 
-Checks for all keywords.
+Checks for all keywords.