Change icons to support linux

Change icons to something displayable in default non-emoji fonts on
linux. Also update README to add screenshots

Author: jgeralnik

README.md

@@ -25,6 +25,11 @@ The above will result in this:<br/>
 or this<br/>
 ![offline indicator](/screenshots/offline_indicator.png)<br/>
 
+On linux the emoji is displayed, instead it will look like this:<br/>
+![online indicator](/screenshots/online_indicator_linux.png)<br/>
+or this<br/>
+![offline indicator](/screenshots/offline_indicator_linux.png)<br/>
+
 The icon will of course change as you connect/disconnect from the internet.
 
 ### Installation with [Tmux Plugin Manager](https://github.com/tmux-plugins/tpm) (recommended)

screenshots/offline_indicator_linux.png

@@ -5,8 +5,8 @@ CURRENT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 online_option_string="@online_icon"
 offline_option_string="@offline_icon"
 
-online_icon_default="✅ "
-offline_icon_default="⛔️ "
+online_icon_default="✔ "
+offline_icon_default="❌ "
 
 source $CURRENT_DIR/shared.sh