Introduce simple character literal

README.md

@@ -23,7 +23,9 @@ afterwards can be a bit cryptic as to where it originated.
 
 - `[operation][number type]`, e.g. `divi` for divide (div) integer
 - `%[register]` for addressing registers
-- `$[value]` for using literals/immediate values
+- `$[value]` for using immediate (literal) integer values
+- `'a'` for using immediate character values (currently only supports non
+escaped characters)
 - `;` for end of statement (mandatory)
 - `[label]:` for labels
 - `#[text]` for comments: any text is ignored till a newline (`\n`) is found
@@ -63,7 +65,8 @@ The following whitespace characters are used to separate symbols:
 - newline (`\n`)
 
 The following characters are used as identifiers:
-- dollar (`$`) for immediate (literal) values
+- dollar (`$`) for immediate (literal) integer values
+- single quote (`'`) for immediate character values
 - percentage (`%`) for register identifiers
 - colon (`:`) for jump labels
 - semicolon (`;`) for statement termination
@@ -86,7 +89,7 @@ second byte of location `$900`).
 All symbols are reserved keywords and can therefore NOT be used as labels.
 There is currently no strict checking, so be careful.
 
-## Preprocessor
+### Preprocessor
 
 All preprocessor directives are prefixed by a `#`. Ill formed preprocessor
 directives do not halt compilation, they are merely reported and then ignored.