Captialize meta.description of all packages

In line with the Nixpkgs manual.

A mechanical change, done with this command:

  find pkgs -name "*.nix" | \
      while read f; do \
          sed -e 's/description\s*=\s*"\([a-z]\)/description = "\u\1/' -i "$f"; \
      done

I manually skipped some:

* Descriptions starting with an abbreviation, a user name or package name
* Frequently generated expressions (haskell-packages.nix)

pkgs/development/ocaml-modules/zarith/default.nix

@@ -27,7 +27,7 @@ stdenv.mkDerivation rec {
   preInstall = "mkdir -p $out/lib/ocaml/${ocaml_version}/site-lib";
 
   meta = with stdenv.lib; {
-    description = "fast, arbitrary precision OCaml integers";
+    description = "Fast, arbitrary precision OCaml integers";
     homepage    = "http://forge.ocamlcore.org/projects/zarith";
     license     = licenses.lgpl2;
     platforms   = ocaml.meta.platforms or [];