RFR: 8157729: examples in LinkedHashMap and LinkedHashSet class doc use raw types

[Stuart Marks]

Add some generics and wrap in `{@code}` to protect angle brackets.

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Commit messages:
 - 8157729: examples in LinkedHashMap and LinkedHashSet class doc use raw types

Changes: https://git.openjdk.java.net/jdk/pull/87/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=87&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8157729
  Stats: 8 lines in 2 files changed: 0 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/87.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/87/head:pull/87

PR: https://git.openjdk.java.net/jdk/pull/87