docs(cli): add docs on installing local package (#6392)

## What's the problem this PR addresses?

Adds documentation on how to install a dependency from your local
filesystem

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<!-- Link all issues that it closes. (Closes/Resolves #xxxx.) -->

...

## How did you fix it?

added some docs

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...

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Co-authored-by: Mark Chambers <[email protected]>

Author: marksy

.yarn/versions/022ed111.yml

@@ -0,0 +1,23 @@
+releases:
+  "@yarnpkg/cli": patch
+  "@yarnpkg/plugin-essentials": patch
+
+declined:
+  - "@yarnpkg/plugin-compat"
+  - "@yarnpkg/plugin-constraints"
+  - "@yarnpkg/plugin-dlx"
+  - "@yarnpkg/plugin-init"
+  - "@yarnpkg/plugin-interactive-tools"
+  - "@yarnpkg/plugin-nm"
+  - "@yarnpkg/plugin-npm-cli"
+  - "@yarnpkg/plugin-pack"
+  - "@yarnpkg/plugin-patch"
+  - "@yarnpkg/plugin-pnp"
+  - "@yarnpkg/plugin-pnpm"
+  - "@yarnpkg/plugin-stage"
+  - "@yarnpkg/plugin-typescript"
+  - "@yarnpkg/plugin-version"
+  - "@yarnpkg/plugin-workspace-tools"
+  - "@yarnpkg/builder"
+  - "@yarnpkg/core"
+  - "@yarnpkg/doctor"

packages/plugin-essentials/sources/commands/add.ts

@@ -63,6 +63,9 @@ export default class AddCommand extends BaseCommand {
     ], [
       `Add a package from a specific branch of a GitHub repository to the current workspace using the GitHub protocol (shorthand)`,
       `$0 add lodash-es@lodash/lodash#es`,
+    ], [
+      `Add a local package (gzipped tarball format) to the current workspace`,
+      `$0 add local-package-name@file:../path/to/local-package-name-v0.1.2.tgz`,
     ]],
   });