update README with plugin prerequisites

Author: d10xa

README.md

@@ -50,6 +50,12 @@ cat log.txt | node ./json-log-viewer/js/target/scala-3.3.1/json-log-viewer-opt/m
 
 Integrate json-log-viewer with k9s to view formatted JSON logs directly within the k9s interface.
 
+### Prerequisites
+For the plugin to work correctly, the following must be installed on your system:
+1. **coursier** - Used to download and run `json-log-viewer` if it's not installed.
+2. **json-log-viewer** (optional) - If already installed, the plugin will use it directly; otherwise, it will fall back to using `coursier` to launch it.
+
+### Installation
 Add the following to your k9s plugin file 
 (usually located at ~/.k9s/plugins.yaml or, on macOS, check the plugin path with `k9s info`):
 
@@ -66,10 +72,16 @@ plugins:
     args:
       - -c
       - |
+        if command -v json-log-viewer >/dev/null 2>&1; then
+          VIEWER_COMMAND="json-log-viewer"
+        else
+          VIEWER_COMMAND="coursier launch ru.d10xa:json-log-viewer_3:latest.release"
+        fi
+
         if [ -n "$POD" ]; then
-          kubectl logs $POD -n $NAMESPACE --context $CONTEXT -c $NAME -f --tail 500 | json-log-viewer; read -p "Press [Enter] to close..."
+          kubectl logs $POD -n $NAMESPACE --context $CONTEXT -c $NAME -f --tail 500 | $VIEWER_COMMAND; read -p "Press [Enter] to close..."
         else
-          kubectl logs $NAME -n $NAMESPACE --context $CONTEXT -f --tail 500 | json-log-viewer; read -p "Press [Enter] to close..."
+          kubectl logs $NAME -n $NAMESPACE --context $CONTEXT -f --tail 500 | $VIEWER_COMMAND; read -p "Press [Enter] to close..."
         fi
 ```