Formatting, links

[rkhetani]

Issue with formatting of the hidden notes in -> https://github.com/hbctraining/publication_perfect/blob/main/lessons/01_Introduction.md#downloaded-data

Issue with broken links in this lesson (list of broken links below)-> https://github.com/hbctraining/publication_perfect/blob/main/lessons/05_custom_plot_scales_colors.md

• http://www.sthda.com/english/wiki/color-chart-hexadecimal
• http://www.datanovia.com/en/blog/ggplot-legend-title-position-and-labels/