Incomplete documentation of gsl_interp_bsearch()

[Constantine Khrulev]

Dear GSL developers,

First of all, thanks for all your work!

I have one minor complaint: every time I write new code that uses 
gsl_interp_bsearch() I end up opening gsl_interp.h and looking for this 
(very informative) comment: 
https://git.savannah.gnu.org/cgit/gsl.git/tree/interpolation/gsl_interp.h?h=release-2-7#n157.

Please consider including this information in the manual 
(https://www.gnu.org/software/gsl/doc/html/interp.html#c.gsl_interp_bsearch).

Thanks!

--
Constantine