Fix doc build.

Author: smimram

tools/bergman/dune

@@ -15,6 +15,7 @@
  (preprocess (pps js_of_ocaml-ppx))
  (libraries bergmanlib js_of_ocaml)
  (modules bergmanjs)
+ (preprocessor_deps index.html bergman.css)
 )
 
 (executable

tools/kb/dune

@@ -7,4 +7,5 @@
  (modes js)
  (preprocess (pps js_of_ocaml-ppx))
  (libraries alg js_of_ocaml)
+ (preprocessor_deps index.html kb.css)
 )

tools/rewr2/dune

@@ -3,4 +3,5 @@
  (modes js)
  (preprocess (pps js_of_ocaml-ppx))
  (libraries alg str js_of_ocaml)
+ (preprocessor_deps index.html)
 )