[SUGGESTION] Add detailed descriptions for volumes and environment variables

[lukasitaly]

This commit enhances the README file by providing comprehensive and detailed descriptions for the volumes and environment variables used in the Umbrel application manifest. The following changes were made:

• Volumes Section: Each volume variable now includes a clear explanation of its purpose and how it should be utilized within the Docker configuration. This includes details on the main application directory, as well as the data directories for LND and Bitcoin Core.
• System Level Environment Variables: Descriptions for the device hostname and domain name variables have been clarified to help users understand their significance in the context of the Umbrel server.
• Tor Proxy Environment Variables: Added detailed explanations for the Tor proxy IP and port variables, emphasizing their role in routing traffic through the Tor network for enhanced privacy.
• App Specific Environment Variables: Provided in-depth descriptions for the app-specific variables, including the hidden service address, authentication password, and unique seed. This aims to assist developers in configuring their applications effectively.

I found it challenging to fully grasp all the details initially, which motivated me to create this reference. The information was sourced from the Umbrel Apps README, and I recommend creating a similar table for the variables to further enhance clarity and accessibility.

Overall, these enhancements aim to improve the clarity and usability of the README, making it easier for developers to understand and implement the necessary configurations for their applications.

Screenshots

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