Improve developer docs

DEVELOPER_GUIDE.md

@@ -32,14 +32,17 @@ Links:
 
 ## Excel add-in
 
-Install the addin in Excel by going to `Developer` > `Excel Add-in` > `Browse` and pointing to the addin in the source code,
+* Install the addin in Excel by going to `Developer` > `Excel Add-in` > `Browse` and pointing to the addin in the source code,
 i.e. under `xlwings/addin/xlwings.xlam`.
 
+* Configure the addin manually (by setting `Interpreter` or `Conda Path`/`Conda Env` settings) or run `xlwings config create --force` to create a new `xlwings.conf` file (this is where the ribbon will read/write the configuration to). 
+
 To change the ribbon UI, you need to download the Office RibbonX Editor (only runs on Windows) from 
 https://github.com/fernandreu/office-ribbonx-editor/releases
 
 The code is pure VBA code. The suggested way to edit the VBA code is:
 
+1. In Excel, make sure that `Trust access` to the VBA project object model is enabled under `File` > `Options` > `Trust Center` > `Trust Center Settings` > `Macro Settings`.
 1. Open the VBA editor via `Alt+F11`, then click on the source code of xlwings and unlock it with the password `xlwings`.
 2. Run the following on a command prompt: 
 
@@ -54,6 +57,7 @@ The code is pure VBA code. The suggested way to edit the VBA code is:
 3. Make changes to the source code under `xlwings/addin` in an external editor: the changes are synced automatically to the VBA editor.
 
 
+
 ## Windows dlls
 
 These are used for the UDFs on Windows. The source for the dlls is under `xlwingsdll`. It's written in C++.