_content/.well-known: register libera.chat project

The libera.chat folks have asked that we verify our chat room by temporarily (I will make the follow up to remove this) placing this string in the well-known tree. This would allow the `#go-nuts` channel to have certain protections including reservig the name `#go-*` and the ability to continue using the single `#` (instead of the two ##s for unverified channels). Is it possible the Go team would be okay with merging this temporarily? Thank you.

See golang/go#46281

/cc @danderson

Change-Id: I45e2a658c473e94c4ba6a03e68df02d68273cfa2
GitHub-Last-Rev: 7150aade441d21b06ee1a0634f02b985b0a67a95
GitHub-Pull-Request: golang/website#58
Reviewed-on: https://go-review.googlesource.com/c/website/+/325450
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Cherry Mui <cherryyz@google.com>
diff --git a/_content/.well-known/libera/index.html b/_content/.well-known/libera/index.html
new file mode 100644
index 0000000..7e85a54
--- /dev/null
+++ b/_content/.well-known/libera/index.html
@@ -0,0 +1 @@
+I'm registering with Libera libera-registration-ticket=903