doc/go1.10: fix formatting of 'go tool fix' examples
doc/go1.10: fix formatting of 'go tool fix' examples

Also remove a superfluous </p>

Change-Id: Idca51cdfbd8abc6669f00c80ca3fb7f225ee445c
Reviewed-on: https://go-review.googlesource.com/84015
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

josharian/go,golang/go,codestation/go,codestation/go,golang/go,CAFxX/go,josharian/go,golang/go,CAFxX/go,josharian/go,CAFxX/go,cloudflare/go,nawawi/go,nawawi/go,golang/go,golang/go,CAFxX/go,codestation/go,CAFxX/go,josharian/go,golang/go,cloudflare/go,codestation/go,cloudflare/go,nawawi/go,akutz/go,nawawi/go,codestation/go,codestation/go,akutz/go,akutz/go,Cofyc/go,Cofyc/go,Cofyc/go,nawawi/go,josharian/go,Cofyc/go,golang/go,akutz/go,Cofyc/go,akutz/go,cloudflare/go,nawawi/go,Cofyc/go,josharian/go,codestation/go,nawawi/go,cloudflare/go,nawawi/go,codestation/go,cloudflare/go,CAFxX/go,Cofyc/go,CAFxX/go,josharian/go,Cofyc/go,cloudflare/go,josharian/go,CAFxX/go,christopher-henderson/Go,akutz/go,cloudflare/go,akutz/go,golang/go,akutz/go