README.md in cumo-0.2.2 vs README.md in cumo-0.2.3

- old
+ new

@@ -1,7 +1,5 @@
-**This project is still under development. This project received grant from [Ruby Association Grant 2017](http://www.ruby.or.jp/ja/news/20171206).**
-
 # Cumo
 
 Cumo (pronounced like "koomo") is CUDA-aware numerical library whose interface is highly compatible with [Ruby Numo](https://github.com/ruby-numo).
 This library provides the benefit of speedup using GPU by replacing Numo with only a small piece of codes.
 
@@ -76,17 +74,17 @@
 If you want to switch Numo and Cumo dynamically, following snippets should work:
 
 ```ruby
 if gpu
   require 'cumo/narray'
-  Xumo = Cumo
+  xm = Cumo
 else
   require 'numo/narray'
-  Xumo = Numo
+  xm = Numo
 end
 
-a = Xumo::DFloat.new(3,5).seq
+a = xm::DFloat.new(3,5).seq
 ```
 
 ### Incompatibility With Numo
 
 Following methods behave incompatibly with Numo as default for performance.
@@ -129,21 +127,23 @@
 
 where `id` is an integer.
 
 ### Disable GPU Memory Pool
 
-Set `CUMO_MEMORY_POOL=OFF` environment variable , or
+GPU memory pool is enabled as default. To disable, set `CUMO_MEMORY_POOL=OFF` environment variable , or
 
 ```
 require 'cumo'
 Cumo::CUDA::MemoryPool.disable
 ```
 
-if you found GPU memory pool implementation has a bug.
-
 ## Documentation
 
 See https://github.com/ruby-numo/numo-narray#documentation and replace Numo to Cumo.
+
+## Contributions
+
+This project is still under development. See [issues](https://github.com/sonots/cumo/issues) for future works.
 
 ## Development
 
 Install ruby dependencies:
 