more tech updates

docs/control/tech/README.md

@@ -427,6 +427,7 @@ The above global metadata can be extracted with this [**demo web tool**](../meta
 * **BITR** H10-13: set the compression in Mb/s for the Protune High Bitrate setting. Normally this would be around 100Mb/s, however higher (or lower) rates may be achieved with newer SD Cards.Input Data: MB/s from 2 to 200. e.g. `*BITR=180`
 * **BITH** H10-13: set the compression for LRVs in Mb/s. Normally this would be around 4Mb/s, however higher (or lower) rates may be achieved with newer SD Cards. Input Data: MB/s from 1 to 100. 
 * **BITL** H11-13: controlling the livestream maximum bitrate (up to 8Mbit/s). Input Data: MB/s from 1 to 8.
+* **BOOT** Boot command can be dangerous, but a safe way to use them is to store the script on the SD Card. So the boot command would be `*BOOT="!Lbt"` which attempts to load a file bt from the MISC folder of the SD card. So creating boot command should always use the formatting `*BOOT="!Lbt"!SAVEbt="your script"` e.g. `*BOOT="!Lbt"!SAVEbt=!12:00NmP!S!1R`
 * **BURN** H8-13/MAX: Add date, time and other burn-in text to your video. Input Format (0,height)[yyyy-mm-dd HH:MM:SSaa] examples:   (0,30)Local Time: [HH:MMaa]   (0,26)Local Time: [HH:MM:SSAA]   (0,40)©[yyyy]\ XYZ Inc.   (0,24)Shoot Date [yy/mm/dd]
 * **BRNP** H8-13/MAX: The burn-in position for overlays or LOGO display. Input Data (select 1 of 8): TL, TC, TR, ML,BL, BC, and BR\nT-Top B-Bottom C-Center L-Left and R-Right.
 * **BRNT** H8-13/MAX: The overlays or LOGO display time in seconds. e.g. BRNT=0.016 will display the logo or text overlays only on the first frame. Input Data: 0 is unlimited, or 0.01 to 3600 seconds.