Update README.md

Author: junjihashimoto

README.md

@@ -1,6 +1,6 @@
-# Prebuild libtorch binary for CI
+# Prebuilt libtorch binary for CI
 
-Download prebuild libtorch binaries from pytorch-official-site.
+Download prebuilt libtorch binaries from pytorch-official-site.
 Then upload them to this repo's release-page.
 To do the operations, type following commands.
 
@@ -20,3 +20,19 @@ sudo apt install alien fakeroot
 #Upload libtorch-binaries to github
 > make upload
 ```
+
+# APT
+
+We provide a apt repository of libtorch for ubuntu.
+You can install libtorch with the following command.
+
+```shell
+sudo bash -c "echo deb [trusted=yes] https://github.com/hasktorch/libtorch-binary-for-ci/releases/download/apt ./ > /etc/apt/sources.list.d/libtorch.list"
+sudo apt update
+# For CPU-only
+sudo apt install libtorch=1.8.1+cpu-1
+# For CUDA-10.2
+sudo apt install libtorch=1.8.1+cu102-1
+# For CUDA-11.1
+sudo apt install libtorch=1.8.1+cu111-1
+```