Update install.md

docs/en/shared/install.md

@@ -1,12 +1,12 @@
 ## Downloading
 
-Go to the [Defold download page](http://d.defold.com/stable/) where you will find Download buttons for macOS, Windows and Linux (Ubuntu):
+Go to the [Defold download page](https://d.defold.com/stable/) where you will find Download buttons for macOS, Windows and Linux (Ubuntu):
 
 ![download editor](../shared/images/editor_download.png)
 
 ## Installation
 
-Installation on MacOS
+Installation on macOS
 : The downloaded file is a DMG image containing the program.
 
   1. Locate the file "Defold-x86_64-darwin.dmg" and double click it to open the image.
@@ -14,7 +14,7 @@ Installation on MacOS
 
   To start the editor, open your "Applications" folder and <kbd>double click</kbd> the file "Defold".
 
-  ![Defold MacOS](../shared/images/macos_content.png)
+  ![Defold macOS](../shared/images/macos_content.png)
 
 Installation on Windows
 : The downloaded file is a ZIP archive that needs to be extracted:
@@ -43,3 +43,13 @@ Installation on Linux
   ```
 
   If you run into any problems starting the editor, opening a project or running a Defold game please refer to the [Linux section of the FAQ](/faq/faq.md#linux-issues).
+
+  ## Install an old version
+
+  You can download and install old editor versions using the following link pattern:
+
+  * Windows: https://d.defold.com/archive/%sha1%/stable/editor2/Defold-x86_64-win32.zip
+  * macOS: https://d.defold.com/archive/%sha1%/stable/editor2/Defold-x86_64-darwin.dmg
+  * Linux: https://d.defold.com/archive/%sha1%/stable/editor2/Defold-x86_64-linux.zip
+
+  Replace `%sha1%` by the editor release hash representing the version in question. The hash of each Defold version can be seen on https://d.defold.com/stable/.