IDE.md: Remove old repo.t5.fi M2E update sites, add two more aspectj.dev

 ones

after Miika Vesti provided copies of the old plugin versions. Thanks,
Miika.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

docs/developer/IDE.md

@@ -58,18 +58,17 @@ As of April 2024, AspectJ developer Alexander Kriegisch published a [fork of the
 and corresponding Eclipse update sites here:
   * Eclipse 2024-03 (4.31): https://aspectj.dev/maven/m2eclipse-ajdt/eclipse-2024-03/
   * Eclipse 2022-12 (4.26): https://aspectj.dev/maven/m2eclipse-ajdt/eclipse-2022-12/
+  * Eclipse 2020-12 (4.18): https://aspectj.dev/maven/m2eclipse-ajdt/eclipse-2020-12/
+  * Eclipse 2019-06 (4.12): https://aspectj.dev/maven/m2eclipse-ajdt/eclipse-2019-06/
 
 The project is only maintained on a best-effort basis, and not each update published has a proper new release version.
 If your snapshot does not update properly (Eclipse failing to calculate solutions for installation and saying that the
 plugin is already installed), simply uninstall the "Maven Integration for AJDT (Optional)" feature from Eclipse,
 re-start the IDE and install again from the corresponding update site.
 
 History: The connector between AspectJ Maven Plugin and AJDT had not been maintained for some years, but until 2023
-there was a fairly up-to-date [fork by Miika Vesti (joker1)](https://github.com/joker1/m2eclipse-ajdt) with the
-following update sites, which currently (April 2024) seem to be unavailable:
-  * Eclipse 2022-12 (4.26): https://repo.t5.fi/public/eclipse/m2eclipse-ajdt/eclipse-2022-12/
-  * Eclipse 2020-12 (4.18): https://repo.t5.fi/public/eclipse/m2eclipse-ajdt/eclipse-2020-12/
-  * Eclipse 2019-06 (4.12): https://repo.t5.fi/public/eclipse/m2eclipse-ajdt/eclipse-2019-06/
+there was a fairly up-to-date [fork by Miika Vesti (joker1)](https://github.com/joker1/m2eclipse-ajdt) with update sites on host **repo.t5.fi**, which are
+no longer available. Hence, the **aspectj.dev** ones listed above.
 
 #### Update sites example