build: use 8.2.x branch of material2-docs-content

the issue with broken semver package name has been resolved upstream
add script for updating the content

Author: Splaktar

package.json

@@ -13,6 +13,7 @@
     "pree2e": "webdriver-manager update",
     "e2e": "yarn build-themes && ng e2e",
     "build": "yarn build-themes && ng build",
+    "build:content": "yarn upgrade @angular/material-examples",
     "build:highmem": "yarn build-themes && node --max_old_space_size=8192 ./node_modules/@angular/cli/bin/ng build",
     "build:sm": "ng build --prod --source-map",
     "build-themes": "bash ./tools/build-themes.sh",
@@ -32,7 +33,7 @@
     "@angular/core": "^8.2.9",
     "@angular/forms": "^8.2.9",
     "@angular/material": "^8.2.2",
-    "@angular/material-examples": "angular/material2-docs-content",
+    "@angular/material-examples": "angular/material2-docs-content#8.2.x",
     "@angular/material-experimental": "^8.2.2",
     "@angular/material-moment-adapter": "^8.2.2",
     "@angular/platform-browser": "^8.2.9",

yarn.lock

@@ -204,9 +204,9 @@
   dependencies:
     tslib "^1.9.0"
 
-"@angular/material-examples@angular/material2-docs-content":
-  version "8.2.2-sha-29be7686e"
-  resolved "https://codeload.github.com/angular/material2-docs-content/tar.gz/4ea08adbee93ad268ba0d7b3c815e11ea8d5a139"
+"@angular/material-examples@angular/material2-docs-content#8.2.x":
+  version "8.2.3-sha-0b175c619"
+  resolved "https://codeload.github.com/angular/material2-docs-content/tar.gz/2f6d3a943b95bb12d6f20a84fd665085b772d01c"
   dependencies:
     tslib "^1.7.1"