add $TERM value to health-check

docs/health-check.md

@@ -34,3 +34,11 @@ If can't skip this check by adding the following in your .tmux.conf file:
 ```
 set -g @fingers-skip-health-check '1'
 ```
+
+## Wrong $TERM value
+
+Tmux fingers works better with proper 256 support. Set `@default-terminal` to either `screen-256color` or `xterm-256color`.
+
+```
+set -g @default-terminal "screen-256color"
+```

scripts/health-check.sh

@@ -144,6 +144,11 @@ function perform_health_check() {
     echo "  * WARNING: tmux 2.2+ is recommended"
   fi
 
+  if [[ "$TERM" != "screen-256color" ]] && [[ "$TERM" != "xterm-256color" ]]; then
+    log_message "  * Wrong \$TERM value '$TERM'."
+    healthy=0
+  fi
+
   if [[ $healthy -eq 0 ]]; then
     while [[ $(is_tmux_ready) = 0 ]]; do
       : # waiting for-tmux