doc: Reduce size of images in docs

Since the docs are now in the tree, so are the images in docs.
The patch reduces the size of images to be under control: target
1024x768 and within 128Kb whenever possible (which is possible for
almost all of them).

The patch reduces the size of the tarball from ~10M to ~4.5M

Change-Id: I76768d94540f15d929537c73e232b035cf081c7b
Signed-off-by: Anastasia Klimchuk <aklm@flashrom.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/85445
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

doc/how_to_add_docs.rst

@@ -33,8 +33,8 @@ Misc questions
 
 * We use CC-BY-4.0 license for documentation.
 * Writing style can be formal or informal, it's mostly up to you, the
-  important thing is to make the text clear, readable and unambiguous. You
+  important thing is to make the text clear, readable and unambiguous.
-  can insert images if this really helps the readers to understand the
+* You can insert images if this really helps the readers to understand the
-  instructions.
+  instructions. Please try to target size 1024x768 and within 128Kb whenever possible.
 * Documentation should be relevant to either flashrom usage or flashrom
   development

doc/supported_hw/supported_prog/ft2232_spi.rst

@@ -241,11 +241,11 @@ Pin (JTAG Name)	SPI/Voltage Source		BIOS Chip connector name
 Pictures
 --------
 
-.. image:: Openmoko_0001.jpeg
+.. image:: Openmoko_0001.jpg
 
-.. image:: Openmoko_0002.jpeg
+.. image:: Openmoko_0002.jpg
 
-.. image:: Openmoko_0003.jpeg
+.. image:: Openmoko_0003.jpg
 
 Performances
 ------------