[dev.regabi] all: merge master (5faf941d) into dev.regabi

Merge List:

+ 2021-02-16 5faf941d internal/goversion: update Version to 1.17
+ 2021-02-16 6f3da9d2 README: pull gopher image from website
+ 2021-02-16 098504c7 cmd/link: generate trampoline for inter-dependent packages
+ 2021-02-16 1004a7cb runtime/metrics: update documentation to current interface
+ 2021-02-16 6530f261 doc/go1.16: remove draft notice
+ 2021-02-16 353e1114 doc/go1.16: fix mismatched id attribute
+ 2021-02-16 f0d23c9d internal/poll: netpollcheckerr before sendfile
+ 2021-02-16 0cb34151 doc: remove all docs not tied to distribution
+ 2021-02-16 626ef081 doc: remove install.html and install-source.html
+ 2021-02-16 30641e36 internal/poll: if copy_file_range returns 0, assume it failed
+ 2021-02-15 33d72fd4 doc/faq: update generics entry to reflect accepted proposal
+ 2021-02-15 852ce7c2 cmd/go: provide a more helpful suggestion for "go vet -?"
+ 2021-02-13 66c27093 cmd/link: fix typo in link_test.go

Change-Id: I98f047b79b93c5ceb344dd43408bcb919b23aeb3