Added ConnectionActivity

app/src/main/java/com/example/greenwatch/ConnectionActivity.java

@@ -0,0 +1,27 @@
+package com.example.greenwatch;
+
+import androidx.appcompat.app.AppCompatActivity;
+
+import android.os.Bundle;
+import android.view.View;
+import android.widget.Button;
+
+public class ConnectionActivity extends AppCompatActivity {
+
+    private Button backToMainActivity;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_connection);
+
+        backToMainActivity = (Button) findViewById(R.id.connectionBackToMainActivity);
+
+        backToMainActivity.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                finish();
+            }
+        });
+    }
+}