returns character vector containing inserted html tags
Arguments
v1
character vector containing first row of matrix m (excluding first 2 entries of m)
v2
character vector containing second row of matrix m (excluding first 2 entries of m)
colorMap
character array of colors
Details
see https://stackoverflow.com/questions/47261100/how-to-rotate-text-90-degrees-inline
also need to increase height of row to accommodate rotated text
see https://resultuniversity.com/html/html-table-width-height#:~:text=To%20set%20the%20height%20of%20a%20specific%20row%20in%20an,property%20in%20pixels%20or%20percentages.