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/compression/bzip2/default.nix

@@ -31,7 +31,7 @@ stdenv.mkDerivation rec {
 
   meta = {
     homepage = "http://www.bzip.org";
-    description = "high-quality data compression program";
+    description = "High-quality data compression program";
 
     platforms = stdenv.lib.platforms.all;
     maintainers = [];