dependency-management.md: update niv references

1. A small fixup/typo over an older reference to `niv`;
2. `niv` is not exactly unmaintained - the most recent commit is from less than 2 months ago. Let's rewrite this in a more neutral manner.

source/guides/recipes/dependency-management.md

@@ -63,7 +63,7 @@ See [](./sharing-dependencies) for details, and note that here you have to pass
 
 As an example, we will use the previously created expression with an older version of Nixpkgs.
 
-Enter the development environment, create a new directory, and set up niv with a different version of Nixpkgs:
+Enter the development environment, create a new directory, and set up npins with a different version of Nixpkgs:
 
 ```shell-session
 $ nix-shell
@@ -95,8 +95,9 @@ nix-build .. -A build --arg sources 'import ./npins'
 
 ## Migrating from `niv`
 
-A previous version of this guide recommended using [`niv`](https://github.com/nmattia/niv/), which is not maintained anymore.
-If you have a project using `niv`, import remote source definitions into `npins`:
+A previous version of this guide recommended using [`niv`](https://github.com/nmattia/niv/), a similar pin manager written in Haskell.
+
+If you have a project using `niv`, you can import remote source definitions into `npins`:
 
 ```shell-session
 npins import-niv