Effect size description in documentation

Currently, in the documentation of `pwr.norm.test()`, the effect size argument (i.e. `d=` ) is described as "Effect size d=mu-mu0". However, in the code documentation, you use the standardized effect size:

```
sigma<-15
c<-100
mu<-105
d<-(mu-c)/sigma
pwr.norm.test(d=d,n=20,sig.level=0.05,alternative="greater")
```