add nerves-tips file

fortunes/nerves-tips

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+Run `dmesg` to see log messages from device drivers and the Linux kernel.
+Nerves also routes kernel log messages to the Elixir logger.
+%
+Erlinit is a small program that starts the Erlang VM on boot.
+It has many options - especially for debugging startup issues.
+%
+Nerves automatically reboots devices when the Erlang VM exits.
+You can easily disable it in your config file.
+
+  config :nerves, :erlinit, hang_on_init: true
+%
+Use `mix firmware.unpack` to decompress a local copy of your firmware on host
+and inspect the files within before installing on device%
+%
+See if someone has already implemented support for a sensor or other hardware
+device that you have by checking https://elixir-circuits.github.io/.
+%
+Nerves stores all BEAM files, the Erlang runtime and various support
+libraries/apps in a compressed and read-only SquashFS filesystem.
+%
+Need to write to disk? Use the application partition mounted R/W at `/data`.
+%
+Configuring the Elixir Logger to show SASL reports can help debug unexpected
+GenServer restarts.
+
+  config :logger,
+    handle_otp_reports: true,
+    handle_sasl_reports: true
+%
+Get the default packages for starting a new Nerves project by depending
+on `:nerves_pack`. https://github.com/nerves-project/nerves_pack/
+%
+Nerves enables hardware watchdogs and connects them to Erlang's heart feature
+to detect and recover from the Erlang VM hanging.
+https://embedded-elixir.com/post/2018-12-10-heart/
+%
+Make small code changes to your running application by copy/pasting Elixir
+source files at the IEx prompt.
+%
+Identify your Nerves devices using a unique ID that's already programmed into
+the hardware using the boardid command. Try running `cmd("boardid")` in the IEx.
+https://github.com/nerves-project/boardid
+%
+Nerves maintains a set of examples for common use-cases with devices.
+https://github.com/nerves-project/nerves_examples
+%
+Use `RingLogger.next` to dump the current log buffer to screen.
+%
+Run `log_attach` in the IEx to attach the current session to the Elixir logger
+for live logs.
+%
+Get some insights to Nerves internals with this high level overview of the
+Nerves architecture and choice to use the BEAM VM. https://youtu.be/VzOaSvTcvU4
+%
+Run `Nerves.Runtime.revert` to go back to the previously loaded firmware.
+%
+Use the `RamoopsLogger` backend to store log messages in DRAM that can survive
+unexpected reboots. https://github.com/smartrent/ramoops_logger
+%
+Files saved in /data are persisted across reboots and firmware upgrades.
+Learn more: https://hexdocs.pm/nerves/faq.html#where-can-persistent-data-be-stored
+%