RFR: 8263546: Add "findsym" command to clhsdb.html help file

[Chris Plummer]

Added clhsdb help for findsym, which was missed when the findsym command was recently added. Also fixed a very minor typo in the findpc help.

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Commit messages:
 - Add clhsdb help for findsym command.

Changes: https://git.openjdk.java.net/jdk/pull/2983/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2983&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263546
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2983.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2983/head:pull/2983

PR: https://git.openjdk.java.net/jdk/pull/2983