So that the navigation pane works correctly in browsers.
Some additional doc fixes put in where found (but many more still to go).
Added some dummy .c and .h files to bring the associated docs into line.
makefile changed to allow 'make html' as well as 'make doc' (the latter only does html anyway).
The value '6' was twice in the table and all higher frequencies are
shifted. The values are now fitting the table in 'STM32F05xxx/06xxx advanced
ARM-based 32-bit MCUs', page 101.
PLL frequencies have been measured by selecting
rcc_set_mco(RCC_CFGR_MCO_SYSCLK);
and measuring the output with an oscilloscope. 8, 16, 24, 32, 40 and 48 MHz
work fine from the HSI base.
