Analysis-icu plugin can't be verified - missing plugin-descriptor.properties?

Greetings Folks -

I'm wondering if anyone else is experiencing the same issue. I'm trying to install the analysis-icu plugin for elasticsearch and getting an error saying it can't be verified.

Here's the command I used (based on what the GitHub readme says):
sudo bin/plugin install elasticsearch/elasticsearch-analysis-icu/2.7.0

And the output ...

-> Installing elasticsearch/elasticsearch-analysis-icu/2.7.0...
Trying https://download.elastic.co/elasticsearch/elasticsearch-analysis-icu/elasticsearch-analysis-icu-2.7.0.zip ..
.
Downloading .......................................................................................................
...................................................................................................................
...................................................................................................................
...................................................................................................................
..............................................................................................................DONE
Verifying https://download.elastic.co/elasticsearch/elasticsearch-analysis-icu/elasticsearch-analysis-icu-2.7.0.zip
checksums if available ...
NOTE: Unable to verify checksum for downloaded plugin (unable to find .sha1 or .md5 file to verify)
ERROR: Could not find plugin descriptor 'plugin-descriptor.properties' in plugin zip

I am running Elasticsearch 2.3.1 on Debian 8.3 (the standard GCE Compute Engine build)

/usr/share/elasticsearch$ bin/elasticsearch --version
Version: 2.3.1, Build: bd98092/2016-04-04T12:25:05Z, JVM: 1.8.0_77

/usr/share/elasticsearch$ cat /etc/debian_version
8.3

Any pointers would be greatly appreciated.

Thanks very much

Read https://www.elastic.co/guide/en/elasticsearch/plugins/current/analysis-icu.html

Thank you David! That does indeed work. So - I guess its just the GitHub instructions that are out of date.

Thanks much!