doc: Add missing html redirect entries for mimxrt10{20,60,64}_evk boards
doc: Add missing html redirect entries for mimxrt10{20,60,64}_evk boards

The mimxrt10{20,60,64}_evk board docs were renamed from <board>.rst to
index.rst in commit 0e4ff809d751678b6277739c8134ab3303f63001 but were
missing entries in the html redirect list. Add them.

An entry for mimxrt1015_evk is not added because this board always had
an index.rst board doc.

Signed-off-by: Maureen Helm <87a696db5547fa477bda9f9e0f00013c839c14d3@nxp.com>

galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,Vudentz/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,Vudentz/zephyr,nashif/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,nashif/zephyr,galak/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,nashif/zephyr,Vudentz/zephyr,nashif/zephyr