many: allow for multiple documentations for a Unit

Change internal.Unit.Documentation from a single
internal.Documentation to a slice, so that a Unit can have doc for
multiple build contexts.

However, don't use this ability yet: fetch takes only the first
build context it finds, postgres inserts only the first, frontend
renders only the first, etc.

For golang/go#37232

Change-Id: I17fd1ff2378e0862c029c8077057c207001f6136
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/288217
Trust: Jonathan Amsterdam <jba@google.com>
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Julie Qiu <julie@golang.org>
Reviewed-by: Jamal Carvalho <jamal@golang.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/internal/postgres/insert_module_test.go b/internal/postgres/insert_module_test.go
index b290af58..617e7754 100644
--- a/internal/postgres/insert_module_test.go
+++ b/internal/postgres/insert_module_test.go
@@ -129,7 +129,7 @@ func TestInsertModuleLicenseCheck(t *testing.T) {
 			}
 
 			mod := sample.Module(sample.ModulePath, sample.VersionString, "")
-			checkHasRedistData(mod.Units[0].Readme.Contents, mod.Units[0].Documentation.Source, true)
+			checkHasRedistData(mod.Units[0].Readme.Contents, mod.Units[0].Documentation[0].Source, true)
 			mod.IsRedistributable = false
 			mod.Units[0].IsRedistributable = false
 
@@ -155,7 +155,7 @@ func TestInsertModuleLicenseCheck(t *testing.T) {
 				readme = u.Readme.Contents
 			}
 			if u.Documentation != nil {
-				source = u.Documentation.Source
+				source = u.Documentation[0].Source
 			}
 			checkHasRedistData(readme, source, bypass)
 		})