RFR: 6859: Correction in JMC welcome page

[Suchita Chaturvedi]

Updated some titles for update sites and made it specific to Open source.

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Commit messages:
 - 6859: Correction in JMC welcome page

Changes: https://git.openjdk.java.net/jmc/pull/197/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=197&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-6859
  Stats: 5 lines in 2 files changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jmc/pull/197.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/197/head:pull/197

PR: https://git.openjdk.java.net/jmc/pull/197