fix: minor contributing doc fixes (#8358)

* make it easier to copy/paste commands by removing unecessary `$`
* replace deprecated `--skip-git` param with `--no-git-tag-version --no-push`

Author: reesscot

CONTRIBUTING.md

@@ -53,12 +53,12 @@ This section should get you running with **Amplify JS** and get you familiar wit
 Start by [forking](https://help.github.com/en/github/getting-started-with-github/fork-a-repo) the main branch of [amplify-js](https://github.com/aws-amplify/amplify-js).
 
 ```
-$ git clone git@github.com:[username]/amplify-js.git
-$ cd amplify-js
+git clone git@github.com:[username]/amplify-js.git
+cd amplify-js
 
-$ yarn
-$ yarn bootstrap
-$ yarn build
+yarn
+yarn bootstrap
+yarn build
 ```
 
 > Note: Make sure to always [sync your fork](https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/syncing-a-fork) with main branch of `amplify-js`
@@ -82,14 +82,14 @@ Amplify JS is a monorepo built with `Yarn` and `Lerna`. All the categories of Am
 #### Build step:
 
 ```
-$ yarn build --scope @aws-amplify/auth
+yarn build --scope @aws-amplify/auth
 ```
 
 #### Testing:
 
 ```
-$ yarn run test --scope @aws-amplify/auth
-$ yarn run test --scope @aws-amplify/ui-components
+yarn run test --scope @aws-amplify/auth
+yarn run test --scope @aws-amplify/ui-components
 ```
 
 > Note: There is a commit hook that will run the tests prior to committing. Please make sure if you are going to provide a pull request to be sure you include unit tests with your functionality and that all tests pass.
@@ -102,22 +102,22 @@ The best way to develop locally and test is to link the individual package you
 Run watch mode while editing (auth for example):
 
 ```
-$ npx lerna exec --scope @aws-amplify/auth yarn link
-$ npx lerna exec --scope @aws-amplify/auth yarn build:esm:watch
+npx lerna exec --scope @aws-amplify/auth yarn link
+npx lerna exec --scope @aws-amplify/auth yarn build:esm:watch
 ```
 
 Or run the whole library in watch mode if you are working on multiple packages
 
 ```
-$ yarn build # Build the whole library
-$ yarn link-all # Make all the packages available to link
-$ yarn build:esm:watch # All packages are building ES6 modules in watch mode
+yarn build # Build the whole library
+yarn link-all # Make all the packages available to link
+yarn build:esm:watch # All packages are building ES6 modules in watch mode
 ```
 
 In your sample project, you can now link specific packages
 
 ```
-$ yarn link @aws-amplify/auth
+yarn link @aws-amplify/auth
 ```
 
 These tests are only necessary if you’re looking to contribute a Pull Request. If you’re just playing locally you don’t need them. However if you’re contributing a Pull Request for anything other than bug fixes it would be best to validate that first because depending on the scope of the change.
@@ -130,7 +130,7 @@ To publish in Verdaccio, start a Verdaccio instance and then,
 
 ```
 yarn config set registry http://localhost:4873/
-yarn lerna publish --skip-git --force-publish
+yarn lerna publish --no-git-tag-version --no-push --force-publish
 ```
 
 To publish a local version of a specific package,