Updates important remarks for etags

Author: angelampcosta

src/content/docs/cache/reference/etag-headers.mdx

@@ -82,3 +82,5 @@ The Cloudflare network will take the following actions, depending on the visitor
 * You must set the value in a strong ETag header using double quotes (for example, `etag: "foobar"`). If you use an incorrect format, Cloudflare will remove the ETag header instead of converting it to a weak ETag. 
 
 * If a resource is cacheable and there is a cache miss, Cloudflare does not send ETag headers to the origin server. This is because Cloudflare requires the full response body to fill its cache.
+
+* If your Origin (or R2) applies compression based on `accept-encoding`, the first compression type will be cached. Consider whether strong ETags fit your use case, or use cache key rules to handle different compression types.