doc: add docs for bson_append_double(3)
doc: add docs for bson_append_double(3)

Convey-Compliance/libbson,Convey-Compliance/libbson,paulmelnikow/libbson,remicollet/libbson,paulmelnikow/libbson,4Second2None/libbson_tmp,rcsanchez97/libbson,mapr/libbson,ajdavis/libbson,jqk6/libbson,derickr/libbson,mongodb/libbson,4Second2None/libbson_tmp,remicollet/libbson,alexeyvo/libbson,paulmelnikow/libbson,ksuarz/libbson,ajdavis/libbson,4Second2None/libbson_tmp,remicollet/libbson,derickr/libbson,derickr/libbson,derickr/libbson,bjori/libbson,rayyang2000/libbson,alexeyvo/libbson,mapr/libbson,alexeyvo/libbson,bjori/libbson,Machyne/libbson,mongodbinc-interns/libbson,Machyne/libbson,jqk6/libbson,Machyne/libbson,rcsanchez97/libbson,mapr/libbson,mongodbinc-interns/libbson,4Second2None/libbson_tmp,ksuarz/libbson,paulmelnikow/libbson,Convey-Compliance/libbson,ksuarz/libbson,remicollet/libbson,mongodbinc-interns/libbson,rayyang2000/libbson,rayyang2000/libbson,jqk6/libbson,Machyne/libbson,mongodb/libbson,paulmelnikow/libbson,bjori/libbson,jqk6/libbson,mongodb/libbson,rcsanchez97/libbson,rayyang2000/libbson,mongodbinc-interns/libbson,ajdavis/libbson