Update README.md

README.md

 # mirador-annotations
 
+## Install
+
+```
+git clone gitlab@gitlab.tetras-libre.fr:iiif/mirador/mirador-annotations.git
+cd mirador-annotations/
+git checkout mui5/React17
+git clone gitlab@gitlab.tetras-libre.fr:iiif/mirador/mirador-video.git
+rm -r mirador
+mv mirador-video/ mirador
+cd mirador/
+git checkout 3def696e
+npm install
+cd ..
+npm install
+```
+
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