docs: Fix misspelled TSK
docs: Fix misspelled TSK

Signed-off-by: Kiwamu Okabe <c2a1336bcfc3d1ccf74b7d9773fac3275e228660@gmail.com>
Reviewed-by: Joakim Bech <741f90e2a7f4d9afbad8bd50be20560f4cf38962@linaro.org>

pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os