AdvancedFeaturePkg: Improve sample build instructions

V1: Make the Windows build example current working directory based
instead of arbitrary.
V2: Fix case mismatch in edk2 repo local name.

Cc: Sai Chaganty <rangasai.v.chaganty@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Rebecca Cran <quic_rcran@quicinc.com>
Signed-off-by: Isaac Oram <isaac.w.oram@intel.com>
Reviewed-by: Rebecca Cran <rebecca@quicinc.com>