docs: document GeoJSON location format and stationary device guidance for map widget

[Freddyminu]

Summary

• Documents GeoJSON (Point) location field format, with a caution note about coordinate order ([Longitude, Latitude])
• Fixes "series" → "groups" terminology to match the actual UI label
• Adds a new section (§7) on managing multiple stationary devices via an virtual accumulator device pattern, including guidance on grouping pins by timestamp vs. group field.

Related Issue

#55

[Freddyminu]

Need to update document to remove mention of becoming legacy, mention that Lon is first before Lat.

[Freddyminu]

@vitorfdl I've removed the mention of Legacy from the LatLon Literal.

[vitorfdl]

TagoIo supports two formats for ingestion. When stored, location is always transformed to { type, coordinates }.

I'm afraid the way you're describing the feature would lead people to think they can't send { lat, lng }.

Not sure if this is the correct place to explain this.

[Freddyminu]

TagoIo supports two formats for ingestion. When stored, location is always transformed to { type, coordinates }.

I'm afraid the way you're describing the feature would lead people to think they can't send { lat, lng }.

Not sure if this is the correct place to explain this.

• I believe the best location to explain this is in the sending-data.md file.

• I've removed the explanation of both options in the map widget and simply kept the warning regarding the flipped Lat, Lon values when using geoJSON.