Prepare for 1.4.0 release (#753)

Author: hoechenberger

docs/source/v1.4.md.inc

@@ -1,4 +1,4 @@
-## v1.4.0 (unreleased)
+## v1.4.0 (2023-07-04)
 
 ### :new: New features & enhancements
 
@@ -17,7 +17,7 @@
 ### :bug: Bug fixes
 
 - Fix bug when [`mf_reference_run != runs[0]`]([mne_bids_pipeline._config.mf_reference_run) (#742 by @larsoner)
-- Fix bug with too many JSON files found during empty room matching (#743 by @allermat)
-- Fix bug with outdated info on ch_types config option (#745 by @allermat)
+- Fix bug with too many JSON files found during empty-room discovery (#743 by @allermat)
 - Fix bug where SSP projectors were not added to the report (#747 by @larsoner)
-- Fix bug with documentation issue on data_type config option (#751 by @allermat)
+- Fix documentation of `data_type` configuration option (#751 by @allermat)
+- Fix documentation of `ch_types` configuration option (#745 by @allermat)