Split absolute and relative path examples

The concern before this one already has split sections.

Rather than a block with two mixed concerns, and a need for "or"  text in a mixed-concern example attempting to demonstrate two things at once,
having two blocks makes it much more obvious, distinct, and reference-able (when the reader is only interested in one aspect).

It also simplifies the NU_LIB_DIRS concern a lot. Instead of a long block headline with a lot of mixed information, we do the same as the other concern earlier in the document:
note the information in an important note block.

Author: Kissaki

book/modules/using_modules.md

@@ -75,19 +75,33 @@ The path to the module can be:
   This allows you to install modules to a location that is easily accessible via a relative path regardless of the current directory.
   :::
 
-- An absolute or relative path to a Nushell module file. As above, Nushell will search the `$env.NU_LIB_DIRS` for a matching relative path.
+- An absolute path to a Nushell module file:
 
   ::: details Example
 
   ```nu
   use ~/nushell/modules/std-rfc/bulk-rename.nu
-  # Or
+  ```
+
+  :::
+
+- A relative path to a Nushell module file:
+
+  ::: details Example
+
+  ```nu
   cd ~/nushell/modules
   use std-rfc/bulk-rename.nu
   ```
 
   :::
 
+  ::: important Important! Importing modules from `$env.NU_LIB_DIRS`
+  When importing a module via a relative path, Nushell first searches from the current directory. If a matching module is not found at that location, Nushell then searches each directory in the `$env.NU_LIB_DIRS` list.
+
+  This allows you to install modules to a location that is easily accessible via a relative path regardless of the current directory.
+  :::
+
 - A virtual directory:
 
   ::: details Example