Update encoding/README.md

Co-authored-by: Sam Sneddon <me@gsnedders.com>

Author: sideshowbarker

encoding/README.md

@@ -28,7 +28,7 @@ the output with the given test data as input.
 For the tests in the `preparsed` subdirectory, the encoding name indicated
 is the expected result of running the *encoding sniffing algorithm* at
 https://html.spec.whatwg.org/#encoding-sniffing-algorithm with the given
-test data as input; this is, it’s the expected result of running *only* the
+test data as input; this is, it's the expected result of running *only* the
 *encoding sniffing algorithm* — without also running the tokenization state
 machine and tree-construction stage defined in the spec.