update: build information

Author: iltgg

docs/Multirotor/Hardware_Manager/index.md

@@ -21,6 +21,14 @@ It appears that when in recovery mode the carrier board does not spin the fan on
 - Install uXRCE-DDS
 - Install/setup Tailscale
 
+Sometimes CUDA doesn't get installed?
+
+```
+sudo apt install cuda-toolkit-12-6
+```
+
+Install custom gstreamer to `/build` or somewhere and point `GST_PLUGIN_PATH` or else library issues!
+
 ### Installing PyTorch
 
 Working method for Jetpack 6.2 and CUDA 12.6:

docs/Multirotor/Tutorials/First_Steps/1._Developer_Environment.md

@@ -129,6 +129,10 @@ Dev Containers will now pull the prebuilt base image from `ghcr.io` and run some
 
 Eventually you should see `Done. Press any key to close the terminal.`
 
+??? note "Building from source"
+    The `DockerFile` is provided in `.devcontainer/Dockerfile`, do something like `docker build dev_env:local .devcontainer` to build the image locally. In order to use the image `devcontainers` is configured to use the `docker-compose.yml` to create and start the container, edit `image` for the `uas` service. <br>
+    Note that this will take a long time (~15 to 30++ minutes).
+
 ??? note "Building on ARM"
     PX4 doesn't support this but if you'd like to try, edit the DockerFile to remove the problematic gcc/g++ libs in `~/PX4-Autopilot/Tools/setup/ubuntu.sh` from the `Installing NuttX dependencies` section and install the multilib packages before running setup script. You will then need to build the container (see the README.md) <br>
     The packages that you might have to install are: