added source.this to setup env

source.this

diff --git a/source.this b/source.this
new file mode 100644
index 0000000..be1ce00
--- /dev/null
+++ b/source.this
@@ -0,0 +1,2 @@
+export PDK_ROOT=/usr/share/pdk/sky130A
+export PRECHECK_ROOT=~/repos/asic/open_mpw_precheck/