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/filesystems/zerofree/default.nix

@@ -17,7 +17,7 @@ stdenv.mkDerivation rec {
 
   meta = {
     homepage = http://intgat.tigress.co.uk/rmy/uml/index.html;
-    description = "zero free blocks from ext2, ext3 and ext4 file-systems";
+    description = "Zero free blocks from ext2, ext3 and ext4 file-systems";
     platforms = stdenv.lib.platforms.linux;
     maintainers = [ stdenv.lib.maintainers.theuni ];
   };