📚 Documentation: Update InputFile documentation about what to use for Flutter Web

[stnguyen90]

💭 Description

On Flutter Web, you must use InputFile.fromBytes(). This was fine in the past because Flutter file/image picker packages didn't provide a path. They've added support for path now, but the path is an Object url and not an actual image path. As such, this path can't be used by the Appwrite SDK.

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• [X] I checked and didn't find similar issue

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[tienthai0205]

@stnguyen90 I could take this issue if it hasn't been worked on?