feat: specify next version in install instructions (#1435)

docs/articles/auth-install.md

@@ -13,7 +13,7 @@ First, let's install the module as it's distributed as npm package. Make sure yo
 Nebular Theme is required to use built-in Auth Components. If you are not going to use those at all, you can use `Auth Module` without the `Nebular Theme` module.  
 
 ```bash
-npm i @nebular/auth
+npm i @nebular/auth@next
 ```
 <hr>
 

docs/articles/install-into-existing.md

@@ -40,7 +40,7 @@ ng new PROJECT-NAME
 Nebular support init configuration with schematics. So, you may just add it to your project.
 
 ```bash
-ng add @nebular/theme
+ng add @nebular/theme@next
 ```
 
 That's it. Nebular has to be ready to go now.
@@ -57,15 +57,15 @@ At this step, we assume you already have Angular modules installed.
 ### Install Nebular modules
 
 ```bash
-npm install --save @nebular/theme @angular/cdk @angular/animations
+npm install --save @nebular/theme@next @angular/cdk @angular/animations
 ```
 Also, you may want to install Eva Icons pack, which is a recommended SVG icons library starting from Nebular 4.0.
 ```bash
-npm install --save @nebular/eva-icons
+npm install --save @nebular/eva-icons@next
 ```
 More details on [how to use Nebular Eva Icons are here](docs/components/icon/overview#nbiconcomponent). 
 
-Additionally you can install Auth and Security `npm install --save @nebular/auth @nebular/security`
+Additionally you can install Auth and Security `npm install --save @nebular/auth@next @nebular/security@next`
 <hr>
 
 ### Configure Nebular

docs/articles/security-install.md

@@ -11,7 +11,7 @@ First, let's install the module as it's distributed as an npm package. Security
 
 
 ```bash
-npm i @nebular/security
+npm i @nebular/security@next
 ```
 <hr>   
 ## Import the module: