[Docs] Fix PlugCharger-v1 dense reward label

[Lidang-Jiang]

Summary

• Fix incorrect dense reward label for PlugCharger-v1 environment
• The environment only supports ["none", "sparse"] reward modes (defined in mani_skill/envs/tasks/tabletop/plug_charger.py line 45), but the documentation incorrectly showed dense reward as supported (✅)
• Updated table row and task card badge to show ❌ for dense reward

Fixes #1368

Evidence

Code: actual SUPPORTED_REWARD_MODES

$ grep -n "SUPPORTED_REWARD_MODES" mani_skill/envs/tasks/tabletop/plug_charger.py
45:    SUPPORTED_REWARD_MODES = ["none", "sparse"]

Diff

diff --git a/docs/source/tasks/table_top_gripper/index.md b/docs/source/tasks/table_top_gripper/index.md
index 348267fc..9842d0aa 100644
--- a/docs/source/tasks/table_top_gripper/index.md
+++ b/docs/source/tasks/table_top_gripper/index.md
@@ -99,7 +99,7 @@ Table of all tasks/environments in this category. Task column is the environment
 <tr class="row-odd">
 <td><p><a href="#plugcharger-v1">PlugCharger-v1</a></p></td>
 <td><div style='display:flex;gap:4px;align-items:center'><img style='min-width:min(50%, 100px);max-width:100px;height:auto' src='../../_static/env_thumbnails/PlugCharger-v1_rt_thumb_first.png' alt='PlugCharger-v1'> <img style='min-width:min(50%, 100px);max-width:100px;height:auto' src='../../_static/env_thumbnails/PlugCharger-v1_rt_thumb_last.png' alt='PlugCharger-v1'></div></td>
-<td><p>✅</p></td>
+<td><p>❌</p></td>
 <td><p>✅</p></td>
 <td><p>✅</p></td>
 <td><p>200</p></td>
@@ -422,7 +422,7 @@ and the sphere is initialized in [-0.1, -0.05] x [-0.1, 0.1]
 
 ## PlugCharger-v1
 
-![dense-reward][dense-reward-badge]
+![no-dense-reward][no-dense-reward-badge]
 ![sparse-reward][sparse-reward-badge]
 ![demos][demos-badge]
 :::{dropdown} Task Card

Test Plan

• Verified SUPPORTED_REWARD_MODES = ["none", "sparse"] in source code matches updated documentation
• Only documentation changes, no code logic affected

[StoneT2000]

thanks!