Fix example in Exercise 1.1.5
Fix example in Exercise 1.1.5

I have fixed the last example in Exercise 1.1.5 which gave two errors:
1. the variable `one` was not defined
2. the package nickname should be `newpack` not `new-pack`
This fixes issue #18
LispTO/llthw,LispTO/llthw,tang-junjie/llthw,tang-junjie/llthw,LispTO/llthw,tang-junjie/llthw