add workspaces configs

Add workspaces-related configs:
  - workspace: list of workspaces names/dir to filter for
  - workspaces: boolean value to enable/disable workspaces awareness

This also adds the proposed note in the docs of each of the commands
that are not affected by these configs.

Relates to: npm/rfcs#117

Author: ruyadorno

docs/content/commands/npm-adduser.md

@@ -12,6 +12,8 @@ npm adduser [--registry=url] [--scope=@orgname] [--always-auth] [--auth-type=leg
 aliases: login, add-user
 ```
 
+Note: This command is unaware of workspaces.
+
 ### Description
 
 Create or verify a user named `<username>` in the specified registry, and

docs/content/commands/npm-bin.md

@@ -10,6 +10,8 @@ description: Display npm bin folder
 npm bin [-g|--global]
 ```
 
+Note: This command is unaware of workspaces.
+
 ### Description
 
 Print the folder where npm will install executables.

docs/content/commands/npm-cache.md

@@ -18,6 +18,8 @@ aliases: npm cache clear, npm cache rm
 npm cache verify
 ```
 
+Note: This command is unaware of workspaces.
+
 ### Description
 
 Used to add, list, or clean the npm cache folder.

docs/content/commands/npm-completion.md

@@ -10,6 +10,8 @@ description: Tab Completion for npm
 source <(npm completion)
 ```
 
+Note: This command is unaware of workspaces.
+
 ### Description
 
 Enables tab-completion in all npm commands.

docs/content/commands/npm-config.md

@@ -18,6 +18,8 @@ npm get [<key> [<key> ...]]
 alias: c
 ```
 
+Note: This command is unaware of workspaces.
+
 ### Description
 
 npm gets its config settings from the command line, environment

docs/content/commands/npm-deprecate.md

@@ -10,6 +10,8 @@ description: Deprecate a version of a package
 npm deprecate <pkg>[@<version range>] <message>
 ```
 
+Note: This command is unaware of workspaces.
+
 ### Description
 
 This command will update the npm registry entry for a package, providing a

docs/content/commands/npm-doctor.md

@@ -10,6 +10,8 @@ description: Check your npm environment
 npm doctor
 ```
 
+Note: This command is unaware of workspaces.
+
 ### Description
 
 `npm doctor` runs a set of checks to ensure that your npm installation has

docs/content/commands/npm-edit.md

@@ -10,6 +10,8 @@ description: Edit an installed package
 npm edit <pkg>
 ```
 
+Note: This command is unaware of workspaces.
+
 ### Description
 
 Selects a dependency in the current project and opens the package folder in

docs/content/commands/npm-explore.md

@@ -10,6 +10,8 @@ description: Browse an installed package
 npm explore <pkg> [ -- <command>]
 ```
 
+Note: This command is unaware of workspaces.
+
 ### Description
 
 Spawn a subshell in the directory of the installed package specified.

docs/content/commands/npm-help-search.md

@@ -10,6 +10,8 @@ description: Search npm help documentation
 npm help-search <text>
 ```
 
+Note: This command is unaware of workspaces.
+
 ### Description
 
 This command will search the npm markdown documentation files for the terms