12.6.0

🚀 Enhancements

• Loading toast styles #852
• Header component #845
• Import .octicon CSS in the core bundle #857
• Design update for blankslates #861
• Don't let State labels wrap #863

📝 Documentation

• Fix some links in linting docs #856
• Updates to the development docs #855
• Generate bundle source READMEs from a template #859
• Render Octicon Ruby helper in docs #847 (fixes https://github.com/primer/css/issue/840)

🏠 Internal

• Add GitHub styleguide.css to Storybook #849