buildroot

website: update package number text

We have quite a bit more than "hundreds of packages" nowadays:

find package -name \*.mk | wc -l
2285

So adjust the text to say 'several thousand' instead.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>