Links to lower case options in documentation are odd

**Description of the problem**

The modules are all described in the on-line documentation (e.g. https://docs.generic-mapping-tools.org/dev/plot.html) with the syntax at the top. There, the *uppercase* options (e.g. **-J**) are clickable and are linked to the descriptions below.

For the *lowercase* options, however, the *option* is not clickable, but the *argument* is. E.g. "flags" is clickable in **-f***flags*, instead of **-f**. This is inconsistent.

In addition, the option **-:** is not linked at all. Neither is **--PAR**=*value*.

This is so across all the documentation of the modules.