Move to the new documentation style with rST formatting.

Signed-off-by: Vasileios Amoiridis <vasileios.amoiridis@cern.ch>

Add support to save boot count variable in ANY filesystem. Tested with
FAT and EXT.

Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Philip Oberfichtner <pro@denx.de>
Signed-off-by: Vasileios Amoiridis <vasileios.amoiridis@cern.ch>

- Grammar fixes
- Clarify explanations

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Reviewed-by: Heiko Schocher <hs@denx.de>

After a successful upgrade, multiple problem during boot sequence may
trigger the altbootcmd process.
This patch adds a version and an upgrade_available entries to the
bootcount file to enable/disable the bootcount check.
When failing to read the bootcount file it will consider that bootcount is
enabled, acting as previously, and update the file accordingly.

The bootcount file is only saved when `upgrade_available` is true, this
allows to save writes to the filesystem.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>
Reviewed-by: Simon Glass <sjg@chromium.org>