Add CodeMash to conference data tracker

[junbuilds96]

Summary

/claim #10

Adds CodeMash to the conference data tracker using public CodeMash sources.

Source notes

• Conference homepage: https://codemash.org/
• Organizer: CodeMash Conference, listed in the CodeMash site footer as an Ohio non-profit organization.
• Speaker benefits source: https://codemash.org/changes-codemash-cfp-2018/
  • The post says CodeMash speakers have consistently been offered a conference ticket, hotel room, speaker thank-you gift, and airport shuttle.
  • It also describes travel grants as reimbursements up to $500.
• I did not find public evidence that CodeMash signs the Speaker Engagement Agreement, so this uses No conservatively per the issue guidance.

Validation

• Preserved the existing Markdown table schema.
• Inserted CodeMash between Code Europe and Functional Scala.
• Ran git diff --check -- README.md.