devel-docs: write dependency name with the namespace casing.

It is apparently how dependency names are supposed to be spelled to be taken
into account. The previous commits fixed some, but missed 2. I'm not sure they
will actually end up in the right-side list of the docs (it looks like when a
dependency is not actually found in the API, it isn't listed there), though it's
at least always listed in the left side, as I can see it.
And while I would prefer the upstream "display" name (i.e. GEGL and babl instead
of Gegl and Babl), better be consistent in how we list these dependencies in the
libgimp and libgimpui docs.

See discussion in !811.

devel-docs/reference/gimp-ui/gimp-ui-3.0.toml.in

@@ -25,7 +25,7 @@ search_index = true
   # These links are mostly used for the dependency lists in index page.
 
   [dependencies."Babl-0.1"]
-  name = "babl"
+  name = "Babl"
   description = "Pixel encoding and color space conversion engine"
   docs_url = "https://gegl.org/babl"
 
@@ -50,7 +50,7 @@ search_index = true
   docs_url = "https://docs.gtk.org/gdk-pixbuf/"
 
   [dependencies."Gegl-0.4"]
-  name = "GEGL"
+  name = "Gegl"
   description = "Generic Graphics Library"
   docs_url = "https://gegl.org/"