Tree is open for general Go 1.18 development

[Carlos Amedee]

Hi gophers!

The early CLs have all landed (see issue 47351), and the tree is now open for general development for the Go 1.18 release.

The doc/go1.18.html draft file will be made available soon (it's CL 342070), so you can start documenting your changes while they're fresh in memory (less work to do at the end of the release!). We will remove all "wait-release" tags on Gerrit CLs (to be replaced with "ex-wait-release"), as well as ping issues in the Go 1.18 milestone that are marked as "early-in-cycle".

I'll copy these points from our past tree reopenings, since they're helpful to keep in mind:

• Check build.golang.org Before Submitting
  
  Before starting to submit your CL or a stack of CLs, please check that the tip is green at https://build.golang.org. If there is a widespread test failure, please wait, or better, help with efforts to diagnose and fix the failure.
  

• Revert Sooner
  
  When a change that landed on master results in a confirmed failure or unintended behavior change, we ask everyone to revert that change sooner, instead of letting it stay merged. For example, if we learn that a change in unspecified behavior of a function like url.Parse causes breakage, then it is better to roll back while thinking about how to address the issue.
  
  This helps ensure master is more stable, making it easier for people who are developing other changes.
  

As always, please proceed cautiously, and happy Go 1.18 development!

Carlos