Add link to Chisel Breakdown slides to README

[jackkoenig]

Provide some useful developer documentation

Contributor Checklist

• [NA] Did you add Scaladoc to every public function/method?
• [NA] Did you add at least one test demonstrating the PR?
• [NA] Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• [NA] Did you add appropriate documentation in docs/src?
• Did you state the API impact?
• Did you specify the code generation impact?
• Did you request a desired merge strategy?
• [NA] Did you add text to be included in the Release Notes for this change?

Type of Improvement

• documentation

API Impact

No impact

Backend Code Generation Impact

No impact

Desired Merge Strategy

• Squash

Release Notes

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels?
• Did you mark the proper milestone (3.2.x, 3.3.x, 3.4.x, 3.5.0) ?
• Did you review?
• Did you check whether all relevant Contributor checkboxes have been checked?
• Did you mark as Please Merge?