Reword `curl | sh` disclaimer in TRPL §2.1
Reword `curl | sh` disclaimer in TRPL §2.1

The paragraph here seemed confusing, so I reworded it.  Also added
another possible reason why `curl | sh` might be objectionable to users.

GBGamer/rust,GBGamer/rust,graydon/rust,graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,GBGamer/rust,graydon/rust,aidancully/rust,aidancully/rust