Update conditional requests documentation on usage with unsage requests. (#54725)

Author: bearcherian

content/rest/using-the-rest-api/best-practices-for-using-the-rest-api.md

@@ -69,7 +69,7 @@ Similarly, you should not try to manually construct pagination queries. Instead,
 
 ## Use conditional requests if appropriate
 
-Most endpoints return an `etag` header, and many endpoints return a `last-modified` header. You can use the values of these headers to make conditional requests. If the response has not changed, you will receive a `304 Not Modified` response. Making a conditional request does not count against your primary rate limit if a `304` response is returned.
+Most endpoints return an `etag` header, and many endpoints return a `last-modified` header. You can use the values of these headers to make conditional `GET` requests. If the response has not changed, you will receive a `304 Not Modified` response. Making a conditional request does not count against your primary rate limit if a `304` response is returned.
 
 For example, if a previous request returned an `etag` header value of `644b5b0155e6404a9cc4bd9d8b1ae730`, you can use the `if-none-match` header in a future request:
 
@@ -83,6 +83,8 @@ For example, if a previous request returned a `last-modified` header value of `W
 curl {% data variables.product.rest_url %}/repos/github/docs --include --header 'if-modified-since: Wed, 25 Oct 2023 19:17:59 GMT'
 ```
 
+Conditional requests for unsafe methods, such as `POST`, `PUT`, `PATCH`, and `DELETE` are not supported unless otherwise noted in the documentation for a specific endpoint.
+
 ## Do not ignore errors
 
 You should not ignore repeated `4xx` and `5xx` error codes. Instead, you should ensure that you are correctly interacting with the API. For example, if an endpoint requests a string and you are passing it a numeric value, you will receive a validation error. Similarly, attempting to access an unauthorized or nonexistent endpoint will result in a `4xx` error.