Add opam descriptions. These fields seem to be required.

dune-project

@@ -57,6 +57,8 @@
  (name pgx_unix)
  (synopsis
    "PGX using the standard library's Unix module for IO (synchronous)")
+ (description
+   "PGX using the standard library's Unix module for IO (synchronous)")
  (depends
   (ocaml
    (>= 4.08))
@@ -66,6 +68,7 @@
 (package
  (name pgx_async)
  (synopsis "Pgx using Async for IO")
+ (description "Pgx using Async for IO")
  (depends
   (alcotest-async
    (and
@@ -85,6 +88,7 @@
 (package
  (name pgx_lwt)
  (synopsis "Pgx using Lwt for IO")
+ (description "Pgx using Lwt for IO")
  (depends
   (alcotest-lwt
    (and
@@ -99,7 +103,8 @@
 
 (package
  (name pgx_lwt_unix)
- (synopsis "Pgx using Lwt for IO")
+ (synopsis "Pgx using Lwt and Unix libraries for IO")
+ (description "Pgx using Lwt and Unix libraries for IO")
  (depends
   (alcotest-lwt
    (and
@@ -116,6 +121,7 @@
 (package
  (name pgx_value_core)
  (synopsis "Pgx_value converters for Core types like Date and Time")
+ (description "Pgx_value converters for Core types like Date and Time")
  (depends
   (core_kernel
    (>= "v0.13.0"))
@@ -126,7 +132,8 @@
 
 (package
  (name pgx_lwt_mirage)
- (synopsis "Pgx using Lwt for IO")
+ (synopsis "Pgx using Lwt on Mirage for IO")
+ (description "Pgx using Lwt on Mirage for IO")
  (depends
   lwt
   (ocaml

pgx_async.opam

@@ -1,6 +1,7 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
 synopsis: "Pgx using Async for IO"
+description: "Pgx using Async for IO"
 maintainer: ["Arena Developers <silver-snakes@arena.io>"]
 authors: ["Arena Developers <silver-snakes@arena.io>"]
 license: "LGPL-2 with OCaml linking exception"

pgx_lwt.opam

@@ -1,6 +1,7 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
 synopsis: "Pgx using Lwt for IO"
+description: "Pgx using Lwt for IO"
 maintainer: ["Arena Developers <silver-snakes@arena.io>"]
 authors: ["Arena Developers <silver-snakes@arena.io>"]
 license: "LGPL-2 with OCaml linking exception"

pgx_lwt_mirage.opam

@@ -1,6 +1,7 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-synopsis: "Pgx using Lwt for IO"
+synopsis: "Pgx using Lwt on Mirage for IO"
+description: "Pgx using Lwt on Mirage for IO"
 maintainer: ["Arena Developers <silver-snakes@arena.io>"]
 authors: ["Arena Developers <silver-snakes@arena.io>"]
 license: "LGPL-2 with OCaml linking exception"

pgx_lwt_unix.opam

@@ -1,6 +1,7 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-synopsis: "Pgx using Lwt for IO"
+synopsis: "Pgx using Lwt and Unix libraries for IO"
+description: "Pgx using Lwt and Unix libraries for IO"
 maintainer: ["Arena Developers <silver-snakes@arena.io>"]
 authors: ["Arena Developers <silver-snakes@arena.io>"]
 license: "LGPL-2 with OCaml linking exception"

pgx_unix.opam

@@ -1,6 +1,8 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
 synopsis: "PGX using the standard library's Unix module for IO (synchronous)"
+description:
+  "PGX using the standard library's Unix module for IO (synchronous)"
 maintainer: ["Arena Developers <silver-snakes@arena.io>"]
 authors: ["Arena Developers <silver-snakes@arena.io>"]
 license: "LGPL-2 with OCaml linking exception"

pgx_value_core.opam

@@ -1,6 +1,7 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
 synopsis: "Pgx_value converters for Core types like Date and Time"
+description: "Pgx_value converters for Core types like Date and Time"
 maintainer: ["Arena Developers <silver-snakes@arena.io>"]
 authors: ["Arena Developers <silver-snakes@arena.io>"]
 license: "LGPL-2 with OCaml linking exception"