Fix most dead links in controller mappings - #878

Changed pages include:

• hardware/manuals.html - view
• chapters/appendix/mixxx_controls.html - view
• hardware/controllers/akai_lpd8.html - view
• hardware/controllers/akai_mpd24.html - view
• hardware/controllers/allen_heath_xone_k2_k1.html - view
• hardware/controllers/american_audio_radius_2000.html - view
• hardware/controllers/american_audio_vms2.html - view
• hardware/controllers/american_audio_vms4.html - view
• hardware/controllers/arturia_keylab_mk1.html - view
• hardware/controllers/behringer_bcd2000.html - view

There are more changes not included in the list