Bazel DocGen: Add target for generating all reference docs at once.

I tested this changed manually in the git repo.

PiperOrigin-RevId: 439539890

src/main/java/com/google/devtools/build/lib/BUILD

@@ -497,3 +497,26 @@ genrule(
     tools = ["//src/main/java/com/google/devtools/build/docgen:skydoc_bin"],
     visibility = ["//site:__pkg__"],
 )
+
+genrule(
+    name = "gen_reference_docs",
+    srcs = [
+        ":build-encyclopedia.zip",
+        ":command-line-reference.html",
+        ":skylark-library.zip",
+        "//tools/build_defs/repo:doc",
+    ],
+    outs = ["reference-docs.zip"],
+    cmd = "mkdir -p $(@D)/gen_docs/reference/be && " +
+          "cp $(location :command-line-reference.html) $(@D)/gen_docs/reference/ && " +
+          "unzip -q -d $(@D)/gen_docs/reference/be/ $(location :build-encyclopedia.zip) && " +
+          "mkdir -p $(@D)/gen_docs/rules/lib/repo && " +
+          "unzip -q -d $(@D)/gen_docs/rules/lib/ $(location :skylark-library.zip) && " +
+          "tar -xf $(location //tools/build_defs/repo:doc) -C $(@D)/gen_docs/rules/lib/repo/ && " +
+          # Ugly hack: we want to preserve paths relative to gen_docs/,
+          # which means we have to temporarily cd into that directory and zip with -r.
+          "pushd $(@D)/gen_docs && " +
+          "zip -qr tmp.zip . && " +
+          "popd && mv $(@D)/gen_docs/tmp.zip $@",
+    visibility = ["//scripts/docs:__pkg__"],
+)

tools/build_defs/repo/BUILD

@@ -63,5 +63,8 @@ pkg_tar(
     name = "doc",
     srcs = ["%s_md" % (name,) for name in REPO_BZL_FILES] + ["index.md"],
     strip_prefix = "/tools/build_defs/repo",
-    visibility = ["//site:__subpackages__"],
+    visibility = [
+        "//site:__subpackages__",
+        "//src/main/java/com/google/devtools/build/lib:__pkg__",
+    ],
 )