Update Installation

Installation.md

@@ -1 +1,49 @@
-tbd
+## Warning regarding stability
+
+At the point of writing (2024-07-29) the maintainer considers the add-on to be in an experimental state. Although all basic functionality is implemented and manually tested it still needs more  real-world usage to call it stable. It should also be noted that – although the code was carefully written – the developer had no prior experience in developing add-ons for Firefox or Thunderbird and implementation might be faulty due to this.
+
+This is the reason why the add-on is currently not published at the Thunderbird Add-On Marketplace. Nevertheless, this may change at some point in the future. If it will be published users who installed SpaceApper previously might need to manually migrated their data. In this case I will warn in advance and provide further instructions.
+
+## Download
+
+Given you read the warning above and you're willing to take the involved risk, you can download the lasted version from the [releases](https://git.mmk2410.org/mmk2410/SpaceApper/releases/latest) page. The correct file is the one with the `.xpi` file extension.
+
+## Installation
+
+Open the "Add-ons and Themes" page from the Hamburger menu in the top right corner. Make sure that the "Extensions" tab is selected on the left side. Then click on the cog icon just below the search field on the upper left part of the centre view.
+
+Choose the menu entry "Install Add-On From File...", select the `.xpi` file downloaded in the previous step and install it by clicking "Open".
+
+## Permissions
+
+Some web apps allow list only certain user agents, e.g. Asana. Since Thunderbird ships more or less the entire Firefox web engine but sets their own user agent you may be prohibited from accessing those apps.
+
+The extension can inject a recent Firefox user agent (pretending to be Microsoft Windows) but it needs permission to do so. Since it seems impossible to ask for permission for certain sites during runtime, the add-ons requests permission to access your data for ALL websites. However, this permission is not activated by default and also not requested from the user.
+
+It is unclear if this is a faulty implementation in the Add-On or if Add-Ons installed from a file just cannot do this. Albeit, if you need it, you can manually enable it. For this, click on the entry of the add-on in the extensions view and choose the "Permissions" tab there. Then activate the checkbox for the entry "Access your data for all websites".
+
+## Usage
+
+There is also a more elaborate [usage documentation](Usage) available, but the important part is covered here in as few words as possible.
+
+To change the websites that should be added to the Spaces Toolbar go to the extension view in the "Add-Ons and Themes" page click on the tool icon at the "SpaceApper" extension. There you'll find a table containing all currently configured websites. For adding additional websites, click the "Add" button at the bottom and to remove and entry click the "Remove" on the right side of the corresponding entry.
+
+Finally apply and persist your changes by click the purple "Save" button.
+
+**Warning: Currently open tabs might be closed. Make sure you saved your work!**
+
+## Update
+
+Repeat the steps from above. Sadly, there is no alternativ as of now.
+
+If you would like to get notified once a new version get released, you may subscribe to the [Releases RSS feed](https://git.mmk2410.org/mmk2410/SpaceApper/releases.rss).
+
+## Building from source
+
+For building the application package yourself, clone the Git archive and run the following command in the root directory of the application:
+
+```sh
+zip -r spaceapper-dev.xpi .
+```
+
+That's all (for now). If the process should get more complex at some point a bash script will be made available and (of course) documented here.