net/rpc: Add documentation for client.Close
net/rpc: Add documentation for client.Close

Fixes #16678

Change-Id: I48c2825d4fef55a75d2f99640a7079c56fce39db
Reviewed-on: https://go-review.googlesource.com/28370
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

cloudflare/go,codestation/go,cloudflare/go,vsekhar/elastic-go,cloudflare/go,nawawi/go,golang/go,codestation/go,golang/go,golang/go,cloudflare/go,linux-on-ibm-z/go,josharian/go,codestation/go,golang/go,nawawi/go,suncycheng/go,momchil-velikov/go,Cofyc/go,CAFxX/go,josharian/go,ImJasonH/go,vsekhar/elastic-go,cloudflare/go,josharian/go,suncycheng/go,akutz/go,polyverse-security/go,akutz/go,suncycheng/go,CAFxX/go,derekmarcotte/go,Cofyc/go,derekmarcotte/go,ImJasonH/go,suncycheng/go,momchil-velikov/go,akutz/go,linux-on-ibm-z/go,ImJasonH/go,codestation/go,linux-on-ibm-z/go,cloudflare/go,akutz/go,akutz/go,goodlang/good,momchil-velikov/go,vsekhar/elastic-go,momchil-velikov/go,suncycheng/go,akutz/go,CAFxX/go,josharian/go,Cofyc/go,goodlang/good,derekmarcotte/go,goodlang/good,ImJasonH/go,polyverse-security/go,Cofyc/go,codestation/go,linux-on-ibm-z/go,josharian/go,nawawi/go,josharian/go,momchil-velikov/go,polyverse-security/go,vsekhar/elastic-go,CAFxX/go,CAFxX/go,momchil-velikov/go,derekmarcotte/go,ImJasonH/go,vsekhar/elastic-go,Cofyc/go,josharian/go,polyverse-security/go,cloudflare/go,Cofyc/go,akutz/go,goodlang/good,ImJasonH/go,momchil-velikov/go,codestation/go,golang/go,golang/go,ImJasonH/go,cloudflare/go,christopher-henderson/Go,linux-on-ibm-z/go,Cofyc/go,vsekhar/elastic-go,suncycheng/go,vsekhar/elastic-go,derekmarcotte/go,CAFxX/go,CAFxX/go,derekmarcotte/go,derekmarcotte/go,nawawi/go,goodlang/good,codestation/go,codestation/go,ImJasonH/go,goodlang/good,derekmarcotte/go,polyverse-security/go,golang/go,akutz/go,nawawi/go,linux-on-ibm-z/go,nawawi/go,goodlang/good,suncycheng/go,linux-on-ibm-z/go,linux-on-ibm-z/go,Cofyc/go,polyverse-security/go,josharian/go,nawawi/go,CAFxX/go,polyverse-security/go,nawawi/go,golang/go,suncycheng/go,vsekhar/elastic-go,polyverse-security/go,goodlang/good,momchil-velikov/go