RFR: JDK-8262315: missing ';' in generated entities

[Jonathan Gibbons]

Fix  typo-by-omission.  A `;` is missing after `&gt`.

This is in the build tools, in the code for the `@jls` taglet, used to generate docs. No change to JDK product code.

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Commit messages:
 - JDK-8262315: missing ';' in generated entities

Changes: https://git.openjdk.java.net/jdk/pull/2709/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2709&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262315
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2709.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2709/head:pull/2709

PR: https://git.openjdk.java.net/jdk/pull/2709