Create performance-analyst-jd.md
Changed top note to 'perf analyst'
Added bullet point marking
Added bold formatting
Create user-researcher-jd.md
Added full JD plus formatting
Add links and update formatting
Add link to new job descriptions
Update jd formatting
Minor text change in intro
Added two bullets to JD - Nick comments
Minor text changes - Cliff comments
Merge pull request #124 from alphagov/performance-analyst

Adding Performance analyst and user researcher JDs