Apply suggestions from code review

Keep UNIX reference consistent.

website/content/partials/plugins/plugin-location.mdx

@@ -3,7 +3,7 @@ discovered and loaded.
 
 Packer plugins will usually be located within a plugins sub-directory under Packer's main config directory
 [PACKER_CONFIG_DIR](/packer/docs/configure#packer-s-config-directory). If `PACKER_CONFIG_DIR` is
-either not set or empty, a default equal to `$HOME/.config/packer/plugins` on POSIX, or `%APPDATA%\packer.d\plugins` 
+either not set or empty, a default equal to `$HOME/.config/packer/plugins` on UNIX, or `%APPDATA%\packer.d\plugins` 
 for Windows, will be used.
 
 Where applicable, some installation processes such as `packer init` may override the plugin loading process. 
@@ -19,7 +19,7 @@ is set. The `PACKER_PLUGIN_PATH` takes precedences over all other plugin directo
 directory](/packer/docs/configure#packer-s-config-directory)*, if it could be found.
 
 -> **Note:** The `PACKER_PLUGIN_PATH` environment variable can be set to more that one directories;
-for example, ~/custom-dir-1:~/custom-dir-2. Separate directories in the PATH string using a colon (:) on POSIX systems 
+for example, ~/custom-dir-1:~/custom-dir-2. Separate directories in the PATH string using a colon (:) on UNIX systems 
 and a semicolon (;) on Windows systems. The above example path would be able to find a single or multi-component plugin
 in either `~/custom-dir-1/packer/` or `~/custom-dir-2/`.