doc/go1.2.txt: delete 'go doc'

It's nearly useless and for plain 'go doc', 'godoc .' works fine.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/13004044

doc/go1.2.txt

@@ -21,6 +21,7 @@ cmd/gc: three-index slicing to set cap as well as length (CL 10743046).
 cmd/gc: make missing package error fatal (CL 12677043).
 cmd/go: test coverage (CL 10413044).
 cmd/go: add -t flag to 'go get' to download test dependencies (CL 12566046).
+cmd/go: delete 'go doc' (CL 12974043).
 
 archive/zip: add File.DataOffset accessor (CL 12784045).
 bufio: add Reset methods to Reader and Writer (CL 12603049).