Update README and CONTRIBUTING for 0.19 (rapidsai#7778)

Authors:
  - Robert Maynard (https://github.com/robertmaynard)

Approvers:
  - Jake Hemstad (https://github.com/jrhemstad)

URL: rapidsai#7778

CONTRIBUTING.md

@@ -131,13 +131,13 @@ run each time you commit changes.
 
 Compiler requirements:
 
-* `gcc`     version 5.4+
-* `nvcc`    version 10.0+
-* `cmake`   version 3.14.0+
+* `gcc`     version 7.1+
+* `nvcc`    version 10.1+
+* `cmake`   version 3.18.0+
 
 CUDA/GPU requirements:
 
-* CUDA 10.0+
+* CUDA 10.1+
 * NVIDIA driver 410.48+
 * Pascal architecture or better
 

README.md

@@ -65,15 +65,15 @@ Please see the [Demo Docker Repository](https://hub.docker.com/r/rapidsai/rapids
 
 cuDF can be installed with conda ([miniconda](https://conda.io/miniconda.html), or the full [Anaconda distribution](https://www.anaconda.com/download)) from the `rapidsai` channel:
 
-For `cudf version == 0.18` :
+For `cudf version == 0.19` :
 ```bash
 # for CUDA 10.1
 conda install -c rapidsai -c nvidia -c numba -c conda-forge \
-    cudf=0.18 python=3.7 cudatoolkit=10.1
+    cudf=0.19 python=3.7 cudatoolkit=10.1
 
 # or, for CUDA 10.2
 conda install -c rapidsai -c nvidia -c numba -c conda-forge \
-    cudf=0.18 python=3.7 cudatoolkit=10.2
+    cudf=0.19 python=3.7 cudatoolkit=10.2
 
 ```