Reenable presubmits for Bazel@HEAD

Generate docs only on Bazel@HEAD, which doesn't redirect to builtin
rules. Builtin rules have a missing newline in the docs, so the docs
can't be generated from them.

.bazelci/presubmit.yml

diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml
index ea4e85b..1455650 100644
--- a/.bazelci/presubmit.yml
+++ b/.bazelci/presubmit.yml
@@ -1,13 +1,10 @@
 ---
 build_targets: &build_targets
   - "//..."
+  - "-//docs/..."
 test_targets: &test_targets
   - "//..."
-
-build_targets_bzlmod: &build_targets_bzlmod
-  - "//..."
-test_targets_bzlmod: &test_targets_bzlmod
-  - "//..."
+  - "-//docs/..."
 
 buildifier:
   version: latest
@@ -17,6 +14,7 @@
 
 tasks:
   ubuntu2004:
+    name: "Bazel LTS (workspace)"
     build_targets: *build_targets
     build_flags:
       - "--config=nobzlmod"
@@ -24,6 +22,7 @@
     test_flags:
       - "--config=nobzlmod"
   macos:
+    name: "Bazel LTS (workspace)"
     build_targets: *build_targets
     build_flags:
       - "--config=nobzlmod"
@@ -31,6 +30,7 @@
     test_flags:
       - "--config=nobzlmod"
   windows:
+    name: "Bazel LTS (workspace)"
     build_targets: *build_targets
     build_flags:
       - "--config=nobzlmod"
@@ -38,6 +38,7 @@
     test_flags:
       - "--config=nobzlmod"
   ubuntu2004_bzlmod:
+    name: "Bazel LTS (bzlmod)"
     platform: ubuntu2004
     build_targets: *build_targets
     build_flags:
@@ -48,6 +49,7 @@
       - "--config=bzlmod"
       - "--lockfile_mode=error"
   macos_bzlmod:
+    name: "Bazel LTS (bzlmod)"
     platform: macos
     build_targets: *build_targets
     build_flags:
@@ -58,6 +60,7 @@
       - "--config=bzlmod"
       - "--lockfile_mode=error"
   windows_bzlmod:
+    name: "Bazel LTS (bzlmod)"
     platform: windows
     build_targets: *build_targets
     build_flags:
@@ -94,30 +97,45 @@
 #    test_targets: *test_targets
 #    test_flags:
 #      - "--config=nobzlmod"
-#  ubuntu2004_head_bzlmod:
-#    bazel: last_green
-#    platform: ubuntu2004
-#    build_flags:
-#      - "--config=bzlmod"
-#    build_targets: *build_targets_bzlmod
-#    test_flags:
-#      - "--config=bzlmod"
-#    test_targets: *test_targets_bzlmod
-#  macos_head_bzlmod:
-#    bazel: last_green
-#    platform: macos
-#    build_flags:
-#      - "--config=bzlmod"
-#    build_targets: *build_targets_bzlmod
-#    test_flags:
-#      - "--config=bzlmod"
-#    test_targets: *test_targets_bzlmod
-#  windows_head_bzlmod:
-#    bazel: last_green
-#    platform: windows
-#    build_flags:
-#      - "--config=bzlmod"
-#    build_targets: *build_targets_bzlmod
-#    test_flags:
-#      - "--config=bzlmod"
-#    test_targets: *test_targets_bzlmod
+  ubuntu2004_head_bzlmod:
+    name: "Bazel@HEAD (bzlmod)"
+    bazel: last_green
+    platform: ubuntu2004
+    build_flags:
+      - "--config=bzlmod"
+    build_targets: *build_targets
+    test_flags:
+      - "--config=bzlmod"
+    test_targets: *test_targets
+  macos_head_bzlmod:
+    name: "Bazel@HEAD (bzlmod)"
+    bazel: last_green
+    platform: macos
+    build_flags:
+      - "--config=bzlmod"
+    build_targets: *build_targets
+    test_flags:
+      - "--config=bzlmod"
+    test_targets: *test_targets
+  windows_head_bzlmod:
+    name: "Bazel@HEAD (bzlmod)"
+    bazel: last_green
+    platform: windows
+    build_flags:
+      - "--config=bzlmod"
+    build_targets: *build_targets
+    test_flags:
+      - "--config=bzlmod"
+    test_targets: *test_targets
+  docs:
+    name: "Docs"
+    bazel: last_green
+    platform: ubuntu2004
+    build_flags:
+      - "--config=bzlmod"
+    build_targets:
+      - "//docs/..."
+    test_flags:
+      - "--config=bzlmod"
+    test_targets:
+      - "//docs/..."