Update README on how to handle deploying

Signed-off-by: Alexandre Montplaisir <alexmonthy@efficios.com>

README.md

@@ -22,8 +22,7 @@ You can then point depending projects to these locations.
 Adding a new CTF test trace
 ---------------------------
 
-The modules follow the
-[Maven standard directory layout](https://maven.apache.org/guides/introduction/introduction-to-the-standard-directory-layout.html).
+The modules follow the [Maven standard directory layout][].
 
 To add a new CTF test trace, add it to the `ctf/src/main/resources` directory.
 Make sure it is not archived or anything, as this will be exposed as-is to the
@@ -32,5 +31,39 @@ users.
 Then update the `ctf/src/main/java/.../CtfTestTrace.java` file accordingly to
 include the new trace.
 
-Finally, bump the project's minor version (1.1 -> 1.2) in the main pom.xml and
-related `<parent>` blocks.
+Make sure the parameters (event count, etc.) are correct! This project does not
+check those at the moment, but if they are incorrect they **will** fail some
+Trace Compass unit tests. This is a known issue.
+
+Finally, bump the project's minor version (1.1.0 -> 1.2.0) in the main pom.xml
+and related `<parent>` blocks.
+
+
+Deploying the repo and update site
+----------------------------------
+
+The default `mvn deploy` goal, when run from the Eclipse CI servers, will deploy
+to the following locations:
+
+* Standard Maven repo (for use in Maven `<dependency>` blocks)
+  * <http://archive.eclipse.org/tracecompass/tracecompass-test-traces/maven/>
+* p2 update site (for use in Eclipse .target files)
+  * <http://archive.eclipse.org/tracecompass/tracecompass-test-traces/repository/latest/>
+
+When pushing a new version, some extra work is required on the server to update
+the p2 update site. The `/repository/` is directory a actually a
+[p2 composite repository][]. But since the deploy simply overwrites the contents
+of `/repository/latest/`, you need to do the following steps manually:
+
+* Copy the `/latest/` directory to a new directory named after the new version,
+  like `/1.2.0/` (*copy* not *move*, please keep `/latest/` available too).
+* Add a new entry in the `compositeArtifacts.xml` and `compositeContent.xml`
+  files to point to the new directory. Do **not** delete existing entries, other
+  projects or git branches may still be using those.
+
+No extra steps are required for the Maven repo, since the Maven plugin handles
+multi-version deploying automatically.
+
+[Maven standard directory layout]: https://maven.apache.org/guides/introduction/introduction-to-the-standard-directory-layout.html
+[p2 composite repository]: https://wiki.eclipse.org/Equinox/p2/Composite_Repositories_%28new%29
+