Add example files

docs/src/examples/cherenkov_times.md

+# Cherenkov times
+
+In this example, we will pick the best reconstructed muon (from the Jpp muon
+reconstruction chain `JMuon`) in each event and calculate the Cherenkov hit time
+residuals for each triggered hit.
+
+We open the `numucc.root` file from the `KM3NeTTestData` package:
+
+```@example 1
+using KM3io, KM3NeTTestData
+
+f = ROOTFile(datapath("offline", "numucc.root"))
+```
+
+Each event holds a vector of reconstructed tracks (`Vector{Trk}`) behind the
+`.trks` field. This vector contains different stages of reconstruction results
+from a variety of reconstruction algorithms (`JMuon`, `JShower`, `aashower`
+etc.). `KM3io.jl` exports helper functions to pick the best reconstructed track
+for a given reconstruction algorithm. The logic is based on the reference
+implementation in [KM3NeT DataFormat
+tools](https://git.km3net.de/common/km3net-dataformat/-/blob/master/tools/reconstruction.hh).
+The function `bestjppmuon()` can be used to select the best reconstructed `JMuon`
+for a given event:
+
+```@example 1
+evt = f.offline[1]
+m = bestjppmuon(evt)
+```
+

docs/src/examples/offline_data.md

+# Examples
+
+## Offline data
+
+Let's use the `KM3NeTTestData` Julia package which contains all kinds of KM3NeT
+related sample files. The `datapath()` function can be used to get a path to
+such a file. In the following, we will discover the `numucc.root` file which
+contains 10 muon neutrino charged current interaction events.
+
+```@example 1
+using KM3io, KM3NeTTestData
+
+f = ROOTFile(datapath("offline", "numucc.root"))
+```
+
+The `ROOTFile` is the container object which gives access to both the online and
+offline tree. In this case, the online tree is empty
+
+```@example 1
+f.online
+```
+
+and the offline tree holds our 10 MC events:
+
+```@example 1
+f.offline
+```
+
+### Events
+
+To access a single event, you can use the usual indexing syntax:
+
+```@example 1
+some_event = f.offline[5]
+```
+
+or ranges of events:
+
+```@example 1
+events = f.offline[6:9]
+```
+
+Each event consists of a vector of hits, MC hits, tracks and MC tracks. Depending
+on the file, they may be empty. They are accessible via the fields `.hit`, `.mc_hits`, `.trks` and `.mc_trks`.
+
+Let's grab an event:
+
+```@example 1
+evt = f.offline[3]
+```
+
+and have a look at its contents:
+
+```@example 1
+evt.hits
+```