Improve the gallery example for datetime inputs

[michaelgrund]

Fixed typo.

[seisman]

Could you please also change "arguments" to "parameters", following #886?

[michaelgrund]

Could you please also change "arguments" to "parameters", following #886?

done!

[seisman]

The example says:

The region parameter has to include the 𝑥 and 𝑦 axis limits as str in the form date_min/date_max/ymin/ymax.

Since #562, we can directly pass datetime to region. For example:

import pygmt
import datetime

fig = pygmt.Figure()

fig.basemap(
    projection="X15c/5c", 
	region=[datetime.date(2010, 1, 1), datetime.date(2030, 6, 1), 0, 10], 
	frame=["WSen", "af"]
)
fig.show()

Please improve the example.

[michaelgrund]

The example says:

The region parameter has to include the 𝑥 and 𝑦 axis limits as str in the form date_min/date_max/ymin/ymax.

Since #562, we can directly pass datetime to region. For example:

import pygmt
import datetime

fig = pygmt.Figure()

fig.basemap(
    projection="X15c/5c", 
	region=[datetime.date(2010, 1, 1), datetime.date(2030, 6, 1), 0, 10], 
	frame=["WSen", "af"]
)
fig.show()

Please improve the example.

Modified the description.

[seisman]

Could you also please wrap the long lines to 80 chars?