Add getting started with Lora on OpenMV tutorial

[BenjaminDannegard]

For tutorials:

• I double checked the wiring in the schematics/images
• I exported the cover image without background
• I used SVG format for pure vector images
• I updated the metadata.json file of the tutorial
• I updated the metadata.json file of the previous tutorial to contain the "next" link
• I did a spell checking before requesting a review
• I used title case for titles

[sebromero]

@BenjaminDannegard Don't forget to add the reviewer and revision:

❌ The authors' format is incorrect. Trailing spaces missing? in content/tutorials/portenta-h7/vs-openmv-ttn/content.md:null
❌ The reviewer's format is incorrect. Review date added YYYY-MM-DD? in content/tutorials/portenta-h7/vs-openmv-ttn/content.md:null
❌ The revisor's format is incorrect. Revision date correct YYYY-MM-DD? in content/tutorials/portenta-h7/vs-openmv-ttn/content.md:null

[sebromero]

I left a few notes

[sebromero]

@BenjaminDannegard Please add the tutorial to the main metadata.json file so that it shows up in the list. Here: https://github.com/arduino/arduino-pro-content/blob/lora-openmv-gs/content/tutorials/portenta-h7/metadata.json

[CLAassistant]

All committers have signed the CLA.

[sebromero]

@BenjaminDannegard @Lenardgeorge Given that this tutorial will be on the docs website in context of the vision shield, there's no need to add the product to the title. Wdyt?