Updates table content for accessibility (#35526)

Co-authored-by: Laura Coursen <[email protected]>

content/rest/webhooks/index.md

@@ -59,7 +59,16 @@ Callback URLs can use the HTTP protocol.
 
 #### Subscribing
 
-The GitHub PubSubHubbub endpoint is: `{% data variables.product.api_url_code %}/hub`. A successful request with curl looks like:
+The GitHub PubSubHubbub endpoint is `{% data variables.product.api_url_code %}/hub`, which takes the following parameters.
+
+Name | Type | Required | Description
+-----|------|-------|-------
+``hub.mode``|`string` | {% octicon "check" aria-label="Required" %} | Either `subscribe` or `unsubscribe`.
+``hub.topic``|`string` | {% octicon "check" aria-label="Required" %} | The URI of the GitHub repository to subscribe to.  The path must be in the format of `/{owner}/{repo}/events/{event}`.
+``hub.callback``|`string` | {% octicon "x" aria-label="Optional" %} | The URI to receive the updates to the topic.
+``hub.secret``|`string` | {% octicon "x" aria-label="Optional" %} | A shared secret key that generates a hash signature of the outgoing body content.  You can verify a push came from GitHub by comparing the raw request body with the contents of the {% ifversion fpt or ghes or ghec %}`X-Hub-Signature` or `X-Hub-Signature-256` headers{% elsif ghae %}`X-Hub-Signature-256` header{% endif %}. You can see [the PubSubHubbub documentation](https://pubsubhubbub.github.io/PubSubHubbub/pubsubhubbub-core-0.4.html#authednotify) for more details.
+
+A example request with curl looks like:
 
 ``` shell
 curl -u "user" -i \
@@ -71,14 +80,4 @@ curl -u "user" -i \
 
 PubSubHubbub requests can be sent multiple times. If the hook already exists, it will be modified according to the request.
 
-##### Parameters
-
-Name | Type | Description
------|------|--------------
-``hub.mode``|`string` | **Required**. Either `subscribe` or `unsubscribe`.
-``hub.topic``|`string` |**Required**.  The URI of the GitHub repository to subscribe to.  The path must be in the format of `/{owner}/{repo}/events/{event}`.
-``hub.callback``|`string` | The URI to receive the updates to the topic.
-``hub.secret``|`string` | A shared secret key that generates a hash signature of the outgoing body content.  You can verify a push came from GitHub by comparing the raw request body with the contents of the {% ifversion fpt or ghes or ghec %}`X-Hub-Signature` or `X-Hub-Signature-256` headers{% elsif ghae %}`X-Hub-Signature-256` header{% endif %}. You can see [the PubSubHubbub documentation](https://pubsubhubbub.github.io/PubSubHubbub/pubsubhubbub-core-0.4.html#authednotify) for more details.
-
-
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