Add description to web bluetooth samples index page.
Add description to web bluetooth samples index page.

ARRAffinity/samples,GoogleChrome/samples,689/samples,jeffposnick/samples,samthor/samples,beaufortfrancois/samples,689/samples,paullewis/samples,jeffposnick/samples,beaufortfrancois/samples,paullewis/samples,GoogleChrome/samples,ARRAffinity/samples,GoogleChrome/samples,samthor/samples,jpmedley/samples,jeffposnick/samples,dmurph/samples,GoogleChrome/samples,rsolomakhin/samples,samthor/samples,paullewis/samples,dmurph/samples,rsolomakhin/samples,rsolomakhin/samples,689/samples,jpmedley/samples,dmurph/samples,ARRAffinity/samples,beaufortfrancois/samples,jpmedley/samples,jeffposnick/samples,beaufortfrancois/samples,GoogleChrome/samples