Improve documentation around /account/whoami
Improve documentation around /account/whoami

Clarifies: https://github.com/matrix-org/matrix-doc/issues/1135

Signed-off-by: Travis Ralston <f36f6a6abc4b55589c96c71fceedf83e596b8f33@gmail.com>
matrix-org/matrix-doc,matrix-org/matrix-doc,matrix-org/matrix-doc,matrix-org/matrix-doc