ARROW-8564: [Website] Add Ubuntu 20.04 LTS to supported package list
Closes #56 from kou/install-ubuntu-20.04 and squashes the following commits:
34a877f5 <Sutou Kouhei> Add Ubuntu 20.04 LTS to supported package list
Authored-by: Sutou Kouhei <kou@clear-code.com>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>
diff --git a/install.md b/install.md
index bf2b120..b6911c1 100644
--- a/install.md
+++ b/install.md
@@ -63,6 +63,7 @@
* Ubuntu 16.04 LTS
* Ubuntu 18.04 LTS
* Ubuntu 19.10
+* Ubuntu 20.04 LTS
* CentOS 6
* CentOS 7
* CentOS 8