Update string.md

docs/string.md

@@ -1,6 +1,6 @@
 ### String
 
-Strings are an immutable sequence of characters. String literals can be surrounded with double or single quotes.
+Strings are an immutable sequence of characters. String literals can be surrounded with double or single quotes. Gravity supports UTF-8 strings and characters.
 ```swift
 	var a = "Hello World";  // double quotes
 	var b = 'Hello World';  // single quotes
@@ -58,4 +58,4 @@ Strings can contain inline expressions with backslash and parentheses.
 	var amount = 7
 	var fruit = "apples"
 	var n = "You have \(amount) \(fruit)!"  // n is now "You have 7 apples!"
-```
+```