Improve Debian bullseye instructions

Thanks to the discussion at:
https://github.com/mirukana/mirage/issues/114

docs/INSTALL.md

@@ -238,11 +238,27 @@ sudo apt install qt5-default qt5-qmake qt5-image-formats-plugins \
 
 #### Ubuntu 19.10+, Debian bullseye / apt
 
-Follow the steps for [Ubuntu 19.04](#ubuntu-1904--apt), but instead of
+No need to install libolm manually.
-installing libolm manually:
 
 ```sh
-sudo apt install libolm-dev
+sudo apt update
+sudo apt install qt5-default qt5-qmake qt5-image-formats-plugins \
+                 qml-module-qtquick2 qml-module-qtquick-window2 \
+                 qml-module-qtquick-layouts qml-module-qtquick-dialogs \
+                 qml-module-qt-labs-platform \
+                 qml-module-qtquick-shapes \
+                 qml-module-qt-labs-qmlmodels \
+                 qml-module-qtgraphicaleffects \
+                 qml-module-qtquick-controls2 \
+                 qtdeclarative5-dev \
+                 qtquickcontrols2-5-dev \
+                 libx11-dev libxss-dev libasound2-dev \
+                 python3-dev python3-pip \
+                 qml-module-io-thp-pyotherside \
+                 build-essential git cmake \
+                 libjpeg62-turbo-dev zlib1g-dev libtiff5-dev libwebp-dev \
+                 libopenjp2-7-dev libmediainfo-dev \
+                 libolm-dev
 ```
 
 #### Void Linux / xbps