Edit README

README.md

@@ -55,21 +55,12 @@ The course covers:
 
 ## Python - Working with Data
 
-### xarray
 | Lesson | Exercise | Solution |
 | ------ | -------- | -------- |
-| Introduction to [multidimensional arrays](https://geohackweek.github.io/nDarrays/01-introduction/), [xarray](https://geohackweek.github.io/nDarrays/02-xarray-architecture/) and [indexing](https://geohackweek.github.io/nDarrays/03-label-based-indexing/) | [Exercise 01]() | [Solution 01]() |
-| [Plotting]() and [Indexing]() | [Exercise 02]() | [Solution 02]() |
+| __xarray:__ Introduction to [multidimensional arrays](https://geohackweek.github.io/nDarrays/01-introduction/), [xarray](https://geohackweek.github.io/nDarrays/02-xarray-architecture/) and [indexing](https://geohackweek.github.io/nDarrays/03-label-based-indexing/) | [Exercise 01]() | [Solution 01]() |
+| __xarray:__ [Plotting]() and [Indexing]() | [Exercise 02]() | [Solution 02]() |
 | [GroupBy processing]() and [masking]() | [Exercise 03]() | [Solution 03]() |
-
-### cf-python
-| Lesson | Exercise | Solution |
-| ------ | -------- | -------- |
-| -      |  -       | -        |
-
-### Higher level-libraries
-| Lesson | Exercise | Solution |
-| ------ | -------- | -------- |
+| __cf-python:__ -      |  -       | -        |
 | [matplotlib]() | [Exercise 05]() | [Solution 05]() |
 | [numpy]() | [Exercise 06]() | [Solution 06]() |
 | [netCDF4]() | [Exercise 07]() | [Solution 07]() |