docs: ia64: Fix a typo ("identify mappings")

The correct term here, also used in the next line, is "identity
mappings". "itentify mappings" was probably just a typo.
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Link: https://lore.kernel.org/r/20221101160609.961950-1-j.neuschaefer@gmx.netSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/ia64/aliasing.rst

@@ -61,7 +61,7 @@ Memory Map
     The efi_memmap table is preserved unmodified because the original
     boot-time information is required for kexec.
 
-Kernel Identify Mappings
+Kernel Identity Mappings
 ========================
 
     Linux/ia64 identity mappings are done with large pages, currently