MAINTAINERS: update location of microvm docs

Fixes: e8eee8d3d9 ("docs: Move microvm.rst into the system manual")

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20211012151447.4147923-1-alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

MAINTAINERS

@@ -1609,7 +1609,7 @@ microvm
 M: Sergio Lopez <slp@redhat.com>
 M: Paolo Bonzini <pbonzini@redhat.com>
 S: Maintained
-F: docs/microvm.rst
+F: docs/system/i386/microvm.rst
 F: hw/i386/microvm.c
 F: include/hw/i386/microvm.h
 F: pc-bios/bios-microvm.bin