Update README.md

README.md

+
+## Requirements
+  - python >= 3.8  *won't work with python 3.6*
+  - matplotlib
+  - netcdf4
+  - numpy
+
 ## Install
 
 ```bash
@@ -7,7 +14,6 @@ python3 -m pip install -e .
 
 ```
 
-
 # Usage
 
 ### Create an image from ctl file with command line
@@ -20,7 +26,3 @@ python3 -m plot_ctl --file=mmsst.ctl --var=sst --tnum=0 --output=sst.png
 ```bash
 python3 -m ctler mmsst.ctl mmsst.nc
 ```
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-
-# Known issues
-
-  - Does not work with files containing only one time record
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