doc: fix confusing example in process.md

PR-URL: nodejs/node#12282
Fixes: nodejs/node#12280
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Alexey Orlenko <eaglexrlnk@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>

doc/api/process.md

@@ -1257,9 +1257,12 @@ function maybeSync(arg, cb) {
 This API is hazardous because in the following case:
 
 ```js
-maybeSync(true, () => {
+const maybeTrue = Math.random() > 0.5;
+
+maybeSync(maybeTrue, () => {
   foo();
 });
+
 bar();
 ```