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/applications/misc/tasknc/default.nix

@@ -39,7 +39,7 @@ stdenv.mkDerivation rec {
 
   meta = {
     homepage = "https://github.com/mjheagle8/tasknc";
-    description = "a ncurses wrapper around taskwarrior";
+    description = "A ncurses wrapper around taskwarrior";
     maintainers = [ stdenv.lib.maintainers.matthiasbeyer ];
     platforms = stdenv.lib.platforms.linux; # Cannot test others
   };