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/development/libraries/ldb/default.nix

@@ -25,7 +25,7 @@ stdenv.mkDerivation rec {
   ];
 
   meta = with stdenv.lib; {
-    description = "a LDAP-like embedded database";
+    description = "A LDAP-like embedded database";
     homepage = http://ldb.samba.org/;
     license = licenses.lgpl3Plus;
     maintainers = with maintainers; [ wkennington ];