Add string literals

README.md

@@ -69,6 +69,7 @@ The following characters are used as identifiers:
 - semicolon (`;`) for statement termination
 - hash (`#`) for comments
 - square brackets (`[` and `]`) for addressing memory
+- double quotes (`"`) for string values
 
 ## Memory Model
 
@@ -90,6 +91,8 @@ There is currently no strict checking, so be careful.
 
 - `DECLARE` declares the first label argument to equal the second, immediate
 	value, argument and is used to declare a constant for the virtual machine.
+- `STRING` puts the string value declared as the second argument in the memory
+	memory location of the first immediate argument
 
 ### Operands