Update config.rst: see issue #2410
Update config.rst: see issue #2410

`When a match is above the *medium* recommendation threshold`
->
`When a match is below the *medium* recommendation threshold`

As discussed in issue #2410, which is fixed by this edit.
pkess/beets,jackwilsdon/beets,madmouser1/beets,SusannaMaria/beets,beetbox/beets,jackwilsdon/beets,MyTunesFreeMusic/privacy-policy,SusannaMaria/beets,ibmibmibm/beets,jackwilsdon/beets,madmouser1/beets,jackwilsdon/beets,Kraymer/beets,beetbox/beets,shamangeorge/beets,Kraymer/beets,madmouser1/beets,sampsyo/beets,MyTunesFreeMusic/privacy-policy,sampsyo/beets,MyTunesFreeMusic/privacy-policy,ibmibmibm/beets,ibmibmibm/beets,ibmibmibm/beets,Kraymer/beets,pkess/beets,shamangeorge/beets,Kraymer/beets,beetbox/beets,sampsyo/beets,MyTunesFreeMusic/privacy-policy,shamangeorge/beets,pkess/beets,beetbox/beets,SusannaMaria/beets,sampsyo/beets,shamangeorge/beets,SusannaMaria/beets,pkess/beets,madmouser1/beets