Added backticks to doc (#6706)

## What are you changing in this pull request and why?

I've created this PR to add backticks to $HOME/.bashrc, $HOME/.zshrc and
<PATH_TO_VIRTUAL_ENV_CONFIG>. These were missing and in the doc, these
commands came out as written text instead of code

## Checklist
- [x] I have reviewed the [Content style
guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md)
so my content adheres to these guidelines.
- [ ] The topic I'm writing about is for specific dbt version(s) and I
have versioned it according to the [version a whole
page](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#adding-a-new-version)
and/or [version a block of
content](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#versioning-blocks-of-content)
guidelines.
- [x] I have added checklist item(s) to this list for anything anything
that needs to happen before this PR is merged, such as "needs technical
review" or "change base branch."
- [ ] The content in this PR requires a dbt release note, so I added one
to the [release notes
page](https://docs.getdbt.com/docs/dbt-versions/dbt-cloud-release-notes).
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<!-- vercel-deployment-preview -->
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🚀 Deployment available! Here are the direct links to the updated files:


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https://docs-getdbt-com-git-nfiann-backticks-dbt-labs.vercel.app/docs/core/pip-install

<!-- end-vercel-deployment-preview -->

website/docs/docs/core/pip-install.md

@@ -29,9 +29,9 @@ dbt-env\Scripts\activate			# activate the environment for Windows
 
 #### Create an alias
 
-To activate your dbt environment with every new shell window or session, you can create an alias for the source command in your $HOME/.bashrc, $HOME/.zshrc, or whichever config file your shell draws from. 
+To activate your dbt environment with every new shell window or session, you can create an alias for the source command in your `$HOME/.bashrc`, `$HOME/.zshrc`, or whichever config file your shell draws from. 
 
-For example, add the following to your rc file, replacing <PATH_TO_VIRTUAL_ENV_CONFIG> with the path to your virtual environment configuration.
+For example, add the following to your rc file, replacing `<PATH_TO_VIRTUAL_ENV_CONFIG>` with the path to your virtual environment configuration.
 
 ```shell
 alias env_dbt='source <PATH_TO_VIRTUAL_ENV_CONFIG>/bin/activate'