build: publish docs-content bazel artifacts (#14634)

package.json

@@ -19,8 +19,6 @@
     "e2e": "gulp e2e",
     "deploy": "gulp deploy:devapp",
     "webdriver-manager": "webdriver-manager",
-    "docs": "gulp docs",
-    "api": "gulp api-docs",
     "breaking-changes": "gulp breaking-changes",
     "gulp": "gulp",
     "stage-release": "ts-node --project tools/release/ tools/release/stage-release.ts",
@@ -92,15 +90,10 @@
     "gulp-clean": "^0.3.2",
     "gulp-clean-css": "^3.3.1",
     "gulp-cli": "^2.0.1",
-    "gulp-dom": "^0.9.17",
-    "gulp-flatten": "^0.3.1",
-    "gulp-highlight-files": "^0.0.5",
     "gulp-htmlmin": "^3.0.0",
     "gulp-if": "^2.0.2",
-    "gulp-markdown": "^1.2.0",
     "gulp-rename": "^1.2.2",
     "gulp-sass": "^4.0.2",
-    "gulp-transform": "^2.0.0",
     "gulp-util": "^3.0.8",
     "hammerjs": "^2.0.8",
     "highlight.js": "^9.11.0",