Doxygen comments not shown properly in tooltips

[davidavetyan]

clangd displays doxygen comments as plain text in the tooltip, unlike the default C/C++ extension of VS code. For example for the code below:

/**
    \brief Example function for adding

    \param num1 First number to add
    \param num2 Second number to add

    \return Sum of \p num1 and \p num2
*/
int add(int num1, int num2)
{
    return num1 + num2;
}

C/C++ extension's intellisense shows the tooltip like so:

While clangd shows it like this:

[HighCommander4]

Duplicate of https://github.com/clangd/clangd/issues/529