Fix missing headers in source dist (#71)

Fixes #50 again

ChangeLog.md

@@ -0,0 +1,12 @@
+# Changelog for dear-imgui
+
+## [1.0.1] Initial Hackage release
+
+- Fixed missing headers in source dist.
+
+## [1.0.0]
+
+Initial Hackage release based on 1.83.
+
+[1.0.0]: https://github.com/haskell-game/dear-imgui.hs/tree/v1.0.0
+[1.0.0]: https://github.com/haskell-game/dear-imgui.hs/tree/v1.0.1

README.md

@@ -25,7 +25,7 @@ OpenGL:
 
 ```
 package dear-imgui
-  flags: +sdl +opengl
+  flags: +sdl +opengl3
 ```
 
 With this done, the following module is the "Hello, World!" of ImGui:

dear-imgui.cabal

@@ -1,9 +1,32 @@
 cabal-version: 3.0
+
 name: dear-imgui
-version: 1.0.0
+version: 1.0.1
+author: Oliver Charles
+maintainer: ollie@ocharles.org.uk, aenor.realm@gmail.com
+license: BSD-3-Clause
+
+category: Graphics
+synopsis: Haskell bindings for Dear ImGui.
+description:
+  The package supports multiple rendering backends.
+  Set package flags according to your needs.
+
 build-type: Simple
-data-files:
-  imgui/imgui.h
+extra-source-files:
+  README.md,
+  ChangeLog.md
+
+extra-source-files:
+  imgui/*.h,
+  imgui/backends/*.h,
+  imgui/backends/*.mm,
+  imgui/imconfig.h,
+  imgui/LICENSE.txt
+
+source-repository head
+  type: git
+  location: https://github.com/haskell-game/dear-imgui.hs
 
 flag opengl2
   description: