docs: package aliases

docs/content/cli-commands/npm-install.md

@@ -16,6 +16,7 @@ npm install [<@scope>/]<name>
 npm install [<@scope>/]<name>@<tag>
 npm install [<@scope>/]<name>@<version>
 npm install [<@scope>/]<name>@<version range>
+npm install <alias>@npm:<name>
 npm install <git-host>:<git-user>/<repo-name>
 npm install <git repo url>
 npm install <tarball file>
@@ -113,6 +114,19 @@ after packing it up into a tarball (b).
 
           npm install sax
 
+    * `npm install <alias>@npm:<name>`:
+
+    Install a package under a custom alias. Allows multiple versions of a same-name package side-by-side, more convenient import names for packages with otherwise long ones and using git forks replacements or forked npm packages as replacements. Aliasing works only on your project and does 
+    not rename packages in transitive dependencies. Aliases should follow 
+    the naming conventions stated in [`validate-npm-package-name`](https://www.npmjs.com/package/validate-npm-package-name#naming-rules).
+
+    Examples:
+
+          npm install my-react@npm:react
+          npm install jquery2@npm:jquery@2
+          npm install jquery3@npm:jquery@3
+          npm install npa@npm:npm-package-arg
+
     `npm install` saves any specified packages into `dependencies` by default.
     Additionally, you can control where and how they get saved with some
     additional flags:

lib/install.js

@@ -26,6 +26,7 @@ install.usage = usage(
   '\nnpm install [<@scope>/]<pkg>@<tag>' +
   '\nnpm install [<@scope>/]<pkg>@<version>' +
   '\nnpm install [<@scope>/]<pkg>@<version range>' +
+  '\nnpm install <alias>@npm:<name>' +
   '\nnpm install <folder>' +
   '\nnpm install <tarball file>' +
   '\nnpm install <tarball url>' +