Polish README

Author: NRaillard

README.Rmd

@@ -72,5 +72,5 @@ Download a time series of significant wave height next to the coast of Finistèr
 ```{r data_fetcher, fig.retina=3}
 data <- get_parameters(node = "134865", parameters = "hs")
 str(data)
-plot(data, type = "l")
+if (!is.null(data)) plot(data, type = "l")
 ```

README.md

@@ -87,7 +87,7 @@ str(data)
 #>  $ time: POSIXct[1:8760], format: "1994-01-01 00:00:00" "1994-01-01 01:00:00" ...
 #>  $ hs  : num [1:8760] 4.82 4.98 5.19 5.37 5.48 ...
 #>  - attr(*, "node")= num 134864
-plot(data, type = "l")
+if (!is.null(data)) plot(data, type = "l")
 ```
 
 <img src="man/figures/README-data_fetcher-1.png" alt="" width="100%" style="display: block; margin: auto;" />