Small typo in DEA Mangroves notebook

[robbibt]

Describe the bug/issue "definitons" instead of "definitions": https://docs.dea.ga.gov.au/notebooks/DEA_products/DEA_Mangroves.html#View-the-DEA-Mangroves-class-values-and-definitons

Can probably also remove the capitalisation here: https://docs.dea.ga.gov.au/notebooks/DEA_products/DEA_Mangroves.html#Plotting-Data

[erialC-P]

Also need to remove reference to 'rgb' in docstring for animation plot

[robbibt]

One more (super minor) one: in the other dataset notebooks, these headings are nested:

In the Mangroves ones, they are on the same level:

Think they need to be dropped down one heading level.