docs/introduction: redirect to welcome subpage

This change uses a Netlify server-side redirect so that a user clicking
on the top-level "Introduction" navbar element sees the
/docs/introduction/welcome/ page instead of the page currently served by
/docs/introduction/, which is a contentless category index.

This aligns Introduction with the top-level redirects for the navbar's
Tutorials, How-to Guides, and Concept Guides elements.

Preview-Path: /docs/introduction/
Signed-off-by: Jonathan Matthews <[email protected]>
Change-Id: Ibc186e97e4fec2c3e117de717bc3e8156dc912e8
Dispatch-Trailer: {"type":"trybot","CL":1171272,"patchset":1,"ref":"refs/changes/72/1171272/1","targetBranch":"alpha"}

internal/ci/netlify/netlify.cue

@@ -66,6 +66,9 @@ config: #config & {
 
 	redirects: [...{force: true, status: 302}]
 	redirects: [{
+		from: "/docs/introduction/"
+		to:   "/docs/introduction/welcome/"
+	}, {
 		from: "/docs/tutorial/"
 		to:   "/docs/tutorial/about-these-tutorials/"
 	}, {

netlify.toml

@@ -20,6 +20,12 @@
 [context.production]
   command = "bash _scripts/build.bash --baseURL https://cuelang.org"
 
+[[redirects]]
+  from = "/docs/introduction/"
+  to = "/docs/introduction/welcome/"
+  status = 302
+  force = true
+
 [[redirects]]
   from = "/docs/tutorial/"
   to = "/docs/tutorial/about-these-tutorials/"