Add CodeMash conference data

[nguyenduc071912]

/claim #10

Summary

• Added CodeMash to the conference data table.
• Used the existing six-column schema and placed the row before Code Europe.
• Used conservative values where I did not find a current public Speaker Engagement Agreement commitment.

Source notes

• Conference and organizer: CodeMash public site and FAQ identify CodeMash as organized by volunteers from the professional developer community.
• Speaker benefits: CodeMash speaker information publicly states accepted speakers receive a CodeMash pass and housing support; no public SEA commitment or general speaker-fee policy was found.

Verification

• git diff --check
• Markdown table column-count check: all rows retain 6 columns.

Demo note: this is a static README data change, so there is no interactive UI video to record.