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/tools/cd-dvd/bashburn/default.nix

@@ -44,7 +44,7 @@ stdenv.mkDerivation rec {
   '';
 
   meta = with stdenv.lib; {
-    description = "bash script CD Burner Writer";
+    description = "Bash script CD Burner Writer";
     longDescription = ''
       It might not be the best looking application out there, but it works.
       It’s simple, fast and small, and can handle most things you throw at it.