docs(@angular/cli): Change npm install to yarn to install (#12495)

dependencies.

Author: rsarky

packages/angular/cli/README.md

@@ -162,7 +162,7 @@ You can find more details about changes between versions in [the Releases tab on
 
 ```bash
 git clone https://github.com/angular/angular-cli.git
-npm install
+yarn
 npm run build
 cd dist/@angular/cli
 npm link

yarn.lock

@@ -7541,6 +7541,7 @@ scss-tokenizer@^0.2.3:
 seedrandom@^2.4.4:
   version "2.4.4"
   resolved "https://registry.yarnpkg.com/seedrandom/-/seedrandom-2.4.4.tgz#b25ea98632c73e45f58b77cfaa931678df01f9ba"
+  integrity sha512-9A+PDmgm+2du77B5i0Ip2cxOqqHjgNxnBgglxLcX78A2D6c2rTo61z4jnVABpF4cKeDMDG+cmXXvdnqse2VqMA==
 
 select-hose@^2.0.0:
   version "2.0.0"