Update installation.rst

[Dr-Bernard]

I added two words 'and you' to the sentence under the "Django Channels & Async" subsection of the "Troubleshooting" section of the INSTALLATION page for a better comprehension of the sentence.

Description

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. Your commit message should include this information as well.

Fixes # (issue)

Checklist:

• [ ] I have added the relevant tests for this change.
• [ ] I have added an item to the Pending section of docs/changes.rst.

[matthiask]

Thank you!