Improve docstrings

Author: juliohm

src/transforms/kmedoids.jl

@@ -16,7 +16,7 @@ Optionally, specify a dictionary of `weights` for each column to
 affect the underlying table distance from TableDistances.jl, and
 a random number generator `rng` to obtain reproducible results.
 
-## Examples
+# Examples
 
 ```julia
 KMedoids(3)

src/transforms/spectralindex.jl

@@ -18,7 +18,7 @@ SpectralIndex("NDVI")
 # water index
 SpectralIndex("NDWI")
 
-# specify "R" (red) and "N" (near infra red) columns
+# specify R (red) and N (near infra red) columns
 SpectralIndex("NDVI", R="col1", N="col4")
 ```