Update README.md

Author: martin-henz

README.md

@@ -10,7 +10,7 @@ The evaluators in this section all follow the general style of SICP JS Chapter 4
 
 * [`src/evaluators/source-0.js`](https://github.com/source-academy/source-programs/blob/master/src/evaluators/source-0.js): evaluator for Source §0 (calculator language)
 * [`src/evaluators/source-0pp.js`](https://github.com/source-academy/source-programs/blob/master/src/evaluators/source-0pp.js): evaluator for Source §0++ (calculator language plus conditionals, blocks and sequences)
-* [`src/evaluators/source-4-1.js`](https://github.com/source-academy/source-programs/blob/master/src/evaluators/source-1.js): evaluator for Source §1, described in SICP JS 4.1
+* [`src/evaluators/source-4-1.js`](https://github.com/source-academy/source-programs/blob/master/src/evaluators/source-4-1.js): evaluator for Source §1, described in SICP JS 4.1
 * [`src/evaluators/typed-source.js`](https://github.com/source-academy/source-programs/blob/master/src/evaluators/typed-source.js): evaluator for Typed Source (typed version of a Source §1 sublanguage)
 * [`src/evaluators/source-4-3.js`](https://github.com/source-academy/source-programs/blob/master/src/evaluators/source-4-3.js): meta-circular evaluator for Source §4.3 (non-deterministic programming)