Initial documentation for dart pub unpack (#5775)

Resolves #5695

---------

Co-authored-by: Marya <[email protected]>

src/_includes/pub-subcommands.md

@@ -8,4 +8,5 @@
 * [`publish`](/tools/pub/cmd/pub-lish)
 * [`remove`](/tools/pub/cmd/pub-remove)
 * [`token`](/tools/pub/cmd/pub-token)
-* [`upgrade`](/tools/pub/cmd/pub-upgrade)
+* [`unpack`](/tools/pub/cmd/pub-unpack)
+* [`upgrade`](/tools/pub/cmd/pub-upgrade)

src/content/tools/pub/cmd/pub-token.md

@@ -12,7 +12,7 @@ The `dart pub token` subcommand has three subcommands:
 [`add`][], [`list`][] and [`remove`][].
 
 The `dart pub` command considers the terms _credential_, _token_, _secret_,
-and _secret token_ to be interchangable.
+and _secret token_ to be interchangeable.
 
 [`add`]: #add-a-new-credential
 [`list`]: #return-a-list-of-credentials

src/content/tools/pub/cmd/pub-unpack.md

@@ -0,0 +1,80 @@
+---
+title: dart pub unpack
+description: Downloads a package and unpacks its contents in place.
+---
+
+:::version-note
+The `unpack` subcommand was introduced in Dart 3.4.
+To download the archive of a package with an earlier SDK,
+visit the **Versions** tab of a package on the [pub.dev site]({{site.pub}}).
+:::
+
+_Unpack_ is one of the commands of the [pub tool](/tools/pub/cmd).
+
+```plaintext
+$ dart pub unpack <package>[:descriptor] [--[no-]resolve] [--output=<output directory>] [--[no-]force] [other options]
+```
+
+This command downloads the specified `<package>` and
+extracts its contents to a `<package>-<version>` directory.
+
+For example, the following command downloads and extracts the
+latest stable version of `package:http` from the [pub.dev site]({{site.pub}}),
+to the current directory:
+
+```console
+$ dart pub unpack http
+```
+
+To change the source or version of the downloaded package,
+add a source descriptor after the package name and a colon.
+For example, the following command downloads the `1.2.0` release
+of `package:http` from the pub.dev site:
+
+```console
+$ dart pub unpack http:1.2.0
+```
+
+The source descriptor supports more configuration
+with the same syntax as `dart pub add`.
+To learn more about source descriptors and their syntax, check out
+the [source descriptor][] documentation for `dart pub add`.
+
+[source descriptor]: /tools/pub/cmd/pub-add#source-descriptor
+
+## Options
+
+For options that apply to all pub commands, check out
+[Global options](/tools/pub/cmd#global-options).
+
+### `--force` or `-f` {:#force-option}
+
+Overwrite existing folders that conflict
+with the package folder or its contents during extraction.
+
+### `--[no-]resolve` {:#resolve-option}
+
+By default, `dart pub get` runs automatically to complete
+package resolution after downloading and unpacking a package.
+To disable automatic resolution,
+specify the `--no-resolve` flag:
+
+```console
+$ dart pub unpack http --no-resolve
+```
+
+### `--output=<dir>` or `-o <dir>` {:#output-option}
+
+By default, extract the package to the current directory (`.`).
+To change the directory the package is extracted to,
+specify the desired output directory with the `--output` option.
+
+For example, the following commands unpacks the
+`1.2.0` release of `package:http` to the `local_http_copies` directory.
+
+```console
+$ dart pub unpack http:1.2.0 -o local_http_copies
+```
+
+
+{% render 'pub-problems.md' %}