Re-add missing release notes for 3.4.0
Re-add missing release notes for 3.4.0

The release notes for 3.3.0 -> 3.4.0 went missing.

[ci skip]

PyTables/PyTables,FrancescAlted/PyTables,avalentino/PyTables,PyTables/PyTables,FrancescAlted/PyTables,FrancescAlted/PyTables,avalentino/PyTables,PyTables/PyTables,avalentino/PyTables