[M] Change in flashrom[master]: doc: Convert README to sphinx

[Thomas Heijligen (Code Review)]

Attention is currently required from: Stefan Reinauer, Edward O'Callaghan, Anastasia Klimchuk, Alexander Goncharov.

Thomas Heijligen has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/74216 )

Change subject: doc: Convert README to sphinx
......................................................................

Patch Set 3: Code-Review+1

(2 comments)

Patchset:

PS3: 
I'll later have a final look on the html output

File README.rst:

https://review.coreboot.org/c/flashrom/+/74216/comment/aacb838e_62d08700 
PS2, Line 66: .. code-block::
This is not needed. You can just say

```
To compile on Linux, use::

make

To compile on ....
```
Using two colons will create a single colon and a code block with the following indented lines. The blank lines are important here.