[docker] update image, add README info

README.md

@@ -72,7 +72,14 @@ stack install
 ~/.local/bin/gargantext-init "gargantext.ini"
 ```
 
-For Docker env, run:
+For Docker env, first create the appropriate image:
+
+``` sh
+cd devops/docker
+docker build -t fpco/stack-build:lts-14.27-garg .
+```
+
+then run:
 
 ``` sh
 stack --docker run gargantext-init -- gargantext.ini

devops/docker/Dockerfile

-from fpco/stack-build:lts-14.6
+from fpco/stack-build:lts-14.27
 
 RUN apt-get update && \
     apt-get install -y git libigraph0-dev && \

stack.yaml

@@ -7,7 +7,7 @@ packages:
 
 docker:
   enable: false
-  repo: 'fpco/stack-build:lts-14.6-garg'
+  repo: 'fpco/stack-build:lts-14.27-garg'
   run-args:
     - '--publish=8008:8008'