Update rmdnote on geometry col name

Based on discussion in https://github.com/Robinlovelace/geocompr/commit/d2472619a81306037e1d414cfe219b240d768669 with @Nowosad

03-attribute-operations.Rmd

@@ -72,9 +72,10 @@ Many of these functions, including `rbind()` (for binding rows of data together)
 A key feature of `sf` objects is that they store spatial and non-spatial data in the same way, as columns in a `data.frame` (the geometry column is typically called `geometry`).
 
 ```{block2 type = 'rmdnote'}
-It is important to note that the geometry column of an `sf` object is typically called `geometry`.
-However, `sf`-objects imported from a spatial database might have names such as `wkb_geometry`, `the_geog` or `the_geom`.
-Additionally, an R user can rename the geometry column of an `sf` object however he/she likes. 
+The geometry column of `sf` objects is typically called `geometry` but any name can be used.
+The following command, for example, creates a geometry column named `g`:
+`st_sf(data.frame(n = world$name_long), g = world$geom)`.
+This enables geometries imported from spatial databases to have a variety of names such as `wkb_geometry`, the_geog` and `the_geom`.
 ```
 
 `sf` objects also support `tibble` and `tbl` classes used in the tidyverse, allowing 'tidy' data analysis workflows for spatial data.