Update function name in mojo docs

MakeIsolatedRequest was renamed in https://crrev.com/c/753624.

Change-Id: I1225ce04242adb398693ac0ff4612c9f672754df
Reviewed-on: https://chromium-review.googlesource.com/c/1334663
Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Adithya Srinivasan <adithyas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608011}

mojo/public/cpp/bindings/README.md

@@ -1175,9 +1175,9 @@ over one end of the master interface, or over one end of another associated
 interface which itself already has a master interface.
 
 If you want to test an associated interface endpoint without first
-associating it, you can use `mojo::MakeIsolatedRequest()`. This will create
-working associated interface endpoints which are not actually associated with
-anything else.
+associating it, you can use `mojo::MakeRequestAssociatedWithDedicatedPipe`. This
+will create working associated interface endpoints which are not actually
+associated with anything else.
 
 ### Read more