AP_HAL_ChibiOS: improve md file readability

[Hwurzburg]

Summary

improves list readability by adding bullets,etc.

Classification & Testing (check all that apply and add your own)

• [x ] Checked by a human programmer
• Non-functional change
• [x ] No-binary change
• Infrastructure change (e.g. unit tests, helper scripts)
• Automated test(s) verify changes (e.g. unit test, autotest)
• Tested manually, description below (e.g. SITL)
• Tested on hardware
• Logs attached
• Logs available on request

Description

some param lists in readmes are single spaced, either need intevening blank line or bullet....also spaced "=" to value