Added package to dependency list

Added the erlang-ssh package to the dependency list and the installation
command instructions. The project wouldn't build otherwise.

docs/installation/debian_based_en.md

@@ -12,6 +12,7 @@ This guide will assume you are on Debian Stretch. This guide should also work wi
 * `erlang-tools`
 * `erlang-parsetools`
 * `erlang-eldap`, if you want to enable ldap authenticator
+* `erlang-ssh`
 * `erlang-xmerl`
 * `git`
 * `build-essential`
@@ -49,7 +50,7 @@ sudo dpkg -i /tmp/erlang-solutions_1.0_all.deb
 
 ```shell
 sudo apt update
-sudo apt install elixir erlang-dev erlang-parsetools erlang-xmerl erlang-tools
+sudo apt install elixir erlang-dev erlang-parsetools erlang-xmerl erlang-tools erlang-ssh
 ```
 
 ### Install PleromaBE

docs/installation/debian_based_jp.md

@@ -14,6 +14,7 @@
 - erlang-dev
 - erlang-tools
 - erlang-parsetools
+- erlang-ssh
 - erlang-xmerl (Jessieではバックポートからインストールすること！)
 - git
 - build-essential
@@ -44,7 +45,7 @@ wget -P /tmp/ https://packages.erlang-solutions.com/erlang-solutions_1.0_all.deb
 
 * ElixirとErlangをインストールします、
 ```
-apt update && apt install elixir erlang-dev erlang-parsetools erlang-xmerl erlang-tools
+apt update && apt install elixir erlang-dev erlang-parsetools erlang-xmerl erlang-tools erlang-ssh
 ```
 
 ### Pleroma BE (バックエンド) をインストールします