[Ecall] Update Ecall documentation
[Ecall] Update Ecall documentation

LE_ECALL_STATE_FAILED event clarification.

Resolves: LE-11778
Change-Id: I2318e2c4ccd5127f237b59878c8c86f5d55103bc

legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af