Upgrade the OPAM files to the 2.0 format (reasonml#2244)

Also add docs about releasing manually to OPAM

Author: anmonteiro

descr

@@ -1,4 +1,4 @@
-opam-version: "1.2"
+opam-version: "2.0"
 maintainer: "Jordan Walke <[email protected]>"
 authors: [ "Jordan Walke <[email protected]>" ]
 license: "MIT"
@@ -9,14 +9,19 @@ dev-repo: "git://github.com/facebook/reason.git"
 tags: [ "syntax" ]
 build: [
   ["dune" "build" "-p" name "-j" jobs]
+  ["dune" "runtest" "-p" name "-j" jobs] {with-test}
 ]
-build-test: [["dune" "runtest" "-p" name "-j" jobs]]
 depends: [
-  "dune"                    {build & >= "1.4"}
-  "ocamlfind"               {build}
-  "menhir"                  {>= "20170418"}
-  "merlin-extend"           {>= "0.3"}
+  "ocaml"         {>= "4.02" & < "4.08"}
+  "dune"          {build & >= "1.4"}
+  "ocamlfind"     {build}
+  "menhir"        {>= "20170418"}
+  "merlin-extend" {>= "0.3"}
   "result"
   "ocaml-migrate-parsetree"
 ]
-available: [ ocaml-version >= "4.02" & ocaml-version < "4.08" ]
+synopsis: "Reason: Syntax & Toolchain for OCaml"
+description: """
+Reason gives OCaml a new syntax that is remniscient of languages like
+JavaScript. It's also the umbrella project for a set of tools for the OCaml &
+JavaScript ecosystem."""

reason.opam

@@ -1,4 +1,4 @@
-opam-version: "1.2"
+opam-version: "2.0"
 maintainer: "Jordan Walke <[email protected]>"
 authors: [ "Jordan Walke <[email protected]>" ]
 license: "MIT"
@@ -9,11 +9,11 @@ dev-repo: "git://github.com/facebook/reason.git"
 tags: [ "syntax" ]
 build: [
   ["dune" "build" "-p" name "-j" jobs]
+  ["dune" "runtest" "-p" name "-j" jobs] {with-test}
 ]
-build-test: [["dune" "runtest" "-p" name "-j" jobs]]
 depends: [
+  "ocaml"  {>= "4.02" & < "4.08"}
   "dune"   {build}
   "reason"
   "utop"   {>= "1.17"}
 ]
-available: [ ocaml-version >= "4.02" & ocaml-version < "4.08" ]

rtop.opam

@@ -306,6 +306,16 @@ env version=x.y.z make release
 
 - Use [opam-publish](https://github.com/ocaml/opam-publish) to publish the latest version to opam.
 
+#### Releasing to OPAM manually
+
+Typically Reason will be released to NPM first (through Esy). To manually release
+to OPAM, simply:
+
+1. Copy the `.opam` file(s) in this repo
+2. Add a `url` clause ([example](https://github.com/ocaml/opam-repository/blob/a55812366d555a5d2ba45cba01fbdab49e459515/packages/reason/reason.3.2.0/opam#L28-L31)) with the place where to find the release tarball.
+3. Submit a PR to the [OPAM repository](https://github.com/ocaml/opam-repository) under e.g.
+`packages/reason/reason.X.Y.Z/opam`.
+
 ### Esy Releases
 
 Cutting a release of esy versions is a good way to get packages out there for