Update README.md

1_taxonomic_profiling_and_vizualization/3_practical_taxonomic_profiling/README.md

 # Practical: Demonstration of mOTUs for taxonomic profiling
 
-Objective of the practical:
+Objectives of the practical:
 - Learn how to create a taxonomic profile for a (quality filtered) metagenomic sample using mOTUs2;
 - Familiarise with the parameters and the output of a taxonomic profiling tool;
 - Learn how to merge many taxonomic profile files (all the profiles from your study) into one file.