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/science/robotics/qgroundcontrol/default.nix

@@ -79,7 +79,7 @@ stdenv.mkDerivation rec {
   };
 
   meta = {
-    description = "provides full ground station support and configuration for the PX4 and APM Flight Stacks";
+    description = "Provides full ground station support and configuration for the PX4 and APM Flight Stacks";
     homepage = http://qgroundcontrol.org/;
     license = stdenv.lib.licenses.gpl3Plus;
     platforms = with stdenv.lib.platforms; linux;