Added installation section to README

Author: ikhomutov

README.md

@@ -1,2 +1,49 @@
 # zsh-auto-venv
 Automatically activate venv when enter the project folder
+
+## Installation
+
+### [antigen](https://github.com/zsh-users/antigen)
+
+1. Add the following to your `.zshrc`:
+
+    ```sh
+    antigen bundle ikhomutov/zsh-auto-venv
+    ```
+
+2. Start a new terminal session.
+
+### [oh-my-zsh](https://github.com/robbyrussell/oh-my-zsh)
+
+1. Clone this repository into `$ZSH_CUSTOM/plugins` (by default `~/.oh-my-zsh/custom/plugins`)
+
+    ```sh
+    git clone https://github.com/ikhomutov/zsh-auto-venv ${ZSH_CUSTOM:-~/.oh-my-zsh/custom}/plugins/zsh-auto-venv
+    ```
+
+2. Add the plugin to the list of plugins for Oh My Zsh to load (inside `~/.zshrc`):
+
+    ```sh
+    plugins=(
+      ...
+      zsh-auto-venv
+    )
+    ```
+
+3. Start a new terminal session.
+
+### Manual (Git Clone)
+
+1. Clone this repository somewhere on your machine. This guide will assume `~/.zsh/zsh-autosuggestions`.
+
+    ```sh
+    git clone https://github.com/ikhomutov/zsh-auto-venv ~/.zsh/zsh-auto-venv
+    ```
+
+2. Add the following to your `.zshrc`:
+
+    ```sh
+    source ~/.zsh/zsh-auto-venv/zsh-auto-venv.zsh
+    ```
+
+3. Start a new terminal session.