[UI] Minor edits of UI captions

Author: peterschmidt85

frontend/src/locale/en.json

@@ -625,14 +625,14 @@
       "name_placeholder": "Optional",
       "name_constraint": "Example: 'my-fleet' or 'default'. If not specified, generated automatically.",
       "min_instances": "Min number of instances",
-      "min_instances_description": "Set it `0` to provision instances only when required",
+      "min_instances_description": "Set it '0' to provision instances only when required",
       "max_instances": "Max number of instances",
       "max_instances_description": "Required only if you want to set an upper limit",
       "max_instances_placeholder": "Optional",
       "idle_duration": "Idle duration",
       "idle_duration_description": "Example: '0s', '1m', '1h'",
       "spot_policy": "Spot policy",
-      "spot_policy_description": "Select spot policy"
+      "spot_policy_description": "Set it to 'auto' to allow the use of both on-demand and spot instances"
     }
   },
   "volume": {

frontend/src/pages/Fleets/Add/FleetFormFields/constants.tsx

@@ -90,7 +90,18 @@ export const FLEET_SPOT_POLICY_INFO = {
     header: <h2>Spot policy</h2>,
     body: (
         <>
-            <p>Spot policy</p>
+            <p>
+                Some backends may support spot instances, also known as preemptive instances. Such instances come at a
+                significantly lower price but can be interrupted by the cloud provider at any time.
+            </p>
+            <p>
+                If you set <code>spot_policy</code> to <code>auto</code>, the fleet will allow the use of both types of
+                instances: <code>on-demand</code> and <code>spot</code>.
+            </p>
+            <p>
+                Note that run configurations must specify their own <code>spot_policy</code>, which by default is always{' '}
+                <code>on-demand</code>.
+            </p>
         </>
     ),
 };