Add README.md

README.md

+Galería
+=======
+
+![Galeria](https://aztlan.fciencias.unam.mx/gitlab/canek/galeria/-/raw/main/static/galeria.png)
+
+**Galería** (Spanish for *gallery*) is a [Django](https://www.djangoproject.com/) webapp to
+provide a simple online photo gallery.
+
+The album structure in Galería es by design simple (or simplistic) and fixed: top albums are
+years, which have month subalbums, which have events subalbums, which  have photographs. Although
+not mandatory, the idea is that each event time range (the period of time between the first
+and last photographs in the event) do not overlap.
+
+Almost all the information in Galería is extracted from the photographs themselves, in their
+metadata; it is expected that each one will have the following tags defined:
+
+* `Exif.Photo.DateTimeOriginal`
+* `Exif.Image.TimeZoneOffset`
+* `Exif.Image.Orientation`
+* `Xmp.dc.subject`
+* `Iptc.Application2.Caption`
+* `Exif.Image.ImageDescription`
+* `Exif.GPSInfo.GPSLatitude`
+* `Exif.GPSInfo.GPSLongitude`
+* `Exif.GPSInfo.GPSLatitudeRef`
+* `Exif.GPSInfo.GPSLongitudeRef`
+
+The `Exif.Photo.DateTimeOriginal` and `Exif.Image.TimeZoneOffset` are used to set a tiemstamp
+for the photograph; without the timezone offset Galería will assume either the server timezone
+or a timezone offset of zero.