Add Release Notes for SALOME 7.4.0

diff --git a/SALOME_7_3_0_Release_Notes.pdf b/SALOME_7_3_0_Release_Notes.pdf
deleted file mode 100755 (executable)
index 99f36ef..0000000
Binary files a/SALOME_7_3_0_Release_Notes.pdf and /dev/null differ

diff --git a/SALOME_7_4_0_Release_Notes.pdf b/SALOME_7_4_0_Release_Notes.pdf
new file mode 100755 (executable)
index 0000000..9030e8b
Binary files /dev/null and b/SALOME_7_4_0_Release_Notes.pdf differ