fixup!

Co-authored-by: ROMemories <[email protected]>

book/src/tooling/coap.md

@@ -106,7 +106,7 @@ A program that triggers a CoAP request provides[^whatsinarequest] some component
   Examples of policies that can be available are
   "expect the server to present some concrete public key, use this secret key once the server is verified",
   "use a token for this audience and scope obtained from that authentication server",
-  "expect the server to present a chain of certificates for its host name down to a set of root certificates" (which is the default for web browsers),
+  "expect the server to present a chain of certificates for its hostname down to a set of root certificates" (which is the default for web browsers),
   "establish an encrypted connection and trust the peer's key on first use"
   down to "do not use any encryption".