fix section headers in docs

Author: jdries

docs/basics.rst

@@ -113,8 +113,7 @@ A job can also be restarted, for instance if an earlier run was aborted:
 
 
 Example: Applying a mask
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 It is very common for earth observation data to have separate masking layers that for instance indicate
 whether a pixel is covered by a (type of) cloud or not. For Sentinel-2, one such layer is the 'scene classification'
 layer that is generated by the Sen2Cor algorithm. In this example, we will use this layer to mask clouds out of our data.
@@ -136,8 +135,7 @@ Once the mask is created, it can be applied to the cube:
    >>> evi_cube_masked = evi_cube.mask(mask.resample_cube_spatial(evi_cube))
 
 Example: Retrieving aggregated timeseries
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 A common type of analysis is aggregating pixel values over one or more regions of interest.
 This is also referred to as 'zonal statistics'. This library has a number of predefined methods
 for various types of aggregations. In this example, we'll show how to compute an