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/idnkit/default.nix

@@ -12,7 +12,7 @@ stdenv.mkDerivation rec {
 
   meta = with stdenv.lib; {
     homepage = https://www.nic.ad.jp/ja/idn/idnkit;
-    description = "provides functionalities about i18n domain name processing";
+    description = "Provides functionalities about i18n domain name processing";
     license = "idnkit-2 license";
     platforms = platforms.unix;
     maintainers = with maintainers; [ wkennington ];