DOC - Improving getting started example

[rcap107]

• Removed section on datasets
• Added replace directives
• Split exploration and cleaning sections

[glemaitre]

Here a couple of comments.

[glemaitre]

Suggested change

	# From the Report above, we can see that there are datetime columns, so we use the
	# |Cleaner| to parse them.
	# From the report above, we see that there are columns with date and time stored
	# as `object` dtype (cf. "Stats" tab of the report). We therefore use the |Cleaner| to
	# parse them and obtain a `datetime` dtype column. We see in the next section that this
	# transformer does additional cleaning.

[glemaitre]

Maybe, we could simplify this text here because it is redundant with the next section. I would propose a broader statement than focusing on the datetime. For instance, we could state that after reading a table, it is common that the dtype are not inferred properly or contains unnecessary columns and that we use the Cleaner for that purpose.

And in the next section, we point out specifically to the datetime column.