Fix figures in design doc (#18612)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

docs/design/kernel/paged_attention.md

@@ -140,22 +140,18 @@ title: vLLM Paged Attention
   const scalar_t* q_ptr = q + seq_idx * q_stride + head_idx * HEAD_SIZE;
   ```
 
-  <figure markdown="span">
-    ![](../../assets/kernel/query.png){ align="center" alt="query" width="70%" }
-    <figcaption>
-</figcaption>
-  </figure>
+<figure markdown="span">
+  ![](../../assets/kernel/query.png){ align="center" alt="query" width="70%" }
+</figure>
 
 - Each thread defines its own `q_ptr` which points to the assigned
   query token data on global memory. For example, if `VEC_SIZE` is 4
   and `HEAD_SIZE` is 128, the `q_ptr` points to data that contains
   total of 128 elements divided into 128 / 4 = 32 vecs.
 
-  <figure markdown="span">
-    ![](../../assets/kernel/q_vecs.png){ align="center" alt="q_vecs" width="70%" }
-    <figcaption>
-</figcaption>
-  </figure>
+<figure markdown="span">
+  ![](../../assets/kernel/q_vecs.png){ align="center" alt="q_vecs" width="70%" }
+</figure>
 
   ```cpp
   __shared__ Q_vec q_vecs[THREAD_GROUP_SIZE][NUM_VECS_PER_THREAD];
@@ -192,11 +188,9 @@ title: vLLM Paged Attention
   points to key token data based on `k_cache` at assigned block,
   assigned head and assigned token.
 
-  <figure markdown="span">
-    ![](../../assets/kernel/key.png){ align="center" alt="key" width="70%" }
-    <figcaption>
-</figcaption>
-  </figure>
+<figure markdown="span">
+  ![](../../assets/kernel/key.png){ align="center" alt="key" width="70%" }
+</figure>
 
 - The diagram above illustrates the memory layout for key data. It
   assumes that the `BLOCK_SIZE` is 16, `HEAD_SIZE` is 128, `x` is
@@ -209,11 +203,9 @@ title: vLLM Paged Attention
   elements for one token) that will be processed by 2 threads (one
   thread group) separately.
 
-  <figure markdown="span">
-    ![](../../assets/kernel/k_vecs.png){ align="center" alt="k_vecs" width="70%" }
-    <figcaption>
-</figcaption>
-  </figure>
+<figure markdown="span">
+  ![](../../assets/kernel/k_vecs.png){ align="center" alt="k_vecs" width="70%" }
+</figure>
 
   ```cpp
   K_vec k_vecs[NUM_VECS_PER_THREAD]
@@ -372,20 +364,14 @@ title: vLLM Paged Attention
 
 <figure markdown="span">
   ![](../../assets/kernel/value.png){ align="center" alt="value" width="70%" }
-  <figcaption>
-</figcaption>
 </figure>
 
 <figure markdown="span">
   ![](../../assets/kernel/logits_vec.png){ align="center" alt="logits_vec" width="50%" }
-  <figcaption>
-</figcaption>
 </figure>
 
 <figure markdown="span">
   ![](../../assets/kernel/v_vec.png){ align="center" alt="v_vec" width="70%" }
-  <figcaption>
-</figcaption>
 </figure>
 
 - Now we need to retrieve the value data and perform dot multiplication