more explanations added

raw_data/explanations.md

@@ -1,15 +1,12 @@
 #### data_R
 * `.RData` and `.r` files are obtained from  [here](http://academic.cengage.com/resource_uploads/downloads/130527010X_514733.zip).
 
-#### data_source
-* `source_5e.txt` is borrowed from [here](https://github.com/JustinMShea/wooldridge/blob/master/data-raw/WooldridgeDataSetHandbook_5eUTF.txt)
-* `source_6e.txt` is also taken from [here](https://github.com/JustinMShea/wooldridge/blob/master/data-raw/WooldridgeDataSetHandbook_6eUTF.txt)
+#### data_csv
+* Created from data files from `.RData` and `.r` files in the `data_R` folder. [pyreadr](https://github.com/ofajardo/pyreadr) is used for `.RData`. Regarding the `.r` files, just replace the file extension with `.csv`.
 
-#### data_description
+#### data_info
 * Extrated from `.RData` which combines data and data description.
 
-#### data_description_space
-* Added four empty columns for files in the `data_description` folder.
-
-#### data_csv
-* Created from data files from `.RData` and `.r` files in the `data_R` folder. Regarding the `.r` files, just replace the file extension with `.csv`.
+#### data_source
+* `source_5e.txt` is borrowed from [here](https://github.com/JustinMShea/wooldridge/blob/master/data-raw/WooldridgeDataSetHandbook_5eUTF.txt)
+* `source_6e.txt` is also taken from [here](https://github.com/JustinMShea/wooldridge/blob/master/data-raw/WooldridgeDataSetHandbook_6eUTF.txt)