-Add auto plugin installation

Author: narfman0

docs/automatic_tpm_installation.md

@@ -2,11 +2,11 @@
 
 One of the first things we do on a new machine is cloning our dotfiles. Not everything comes with them though, so for example `tpm` most likely won't be installed.
 
-If you wanna install `tpm` automatically when tmux is started, put the following snippet in `.tmux.conf` before the final `run '~/.tmux/plugins/tpm/tpm'`:
+If you want to install `tpm` and plugins automatically when tmux is started, put the following snippet in `.tmux.conf` before the final `run '~/.tmux/plugins/tpm/tpm'`:
 
 ```
 if "test ! -d ~/.tmux/plugins/tpm" \
-   "run 'git clone https://github.com/tmux-plugins/tpm ~/.tmux/plugins/tpm'"
+   "run 'git clone https://github.com/tmux-plugins/tpm ~/.tmux/plugins/tpm && ~/.tmux/plugins/tpm/bin/install_plugins'"
 ```
 
-This useful tip was submitted by @acr4.
+This useful tip was submitted by @acr4 and narfman0.