wiki: redirect everything to go.dev/wiki For #61940.
url updates to go.dev / pkg.go.dev
fix godoc.org / pkg.go.dev links
Fix a typo
fix typo - not all developers are 'he'
googlecode is dead
Point to go help get and go help importpath.
Mark a section as out of date.
Change "Goinstall" to "go get"; this is long overdue. Remove some info about Go <1.
PackagePublishing: update wiki internal link
Fix formatting after import
Wiki data import from Google Code