doc: fix nits in esm.md
Checklist
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make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
documentation is changed or added -
commit message follows commit guidelines
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```mjs
->```js
as our linting of doc code fragments does not recognize this tag, IIRC. -
Add semicolons to a code fragment.
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Fix ASCII sorting in bottom references.