spelling: substitution

SECURITY.md

@@ -46,7 +46,7 @@ do two things:
 
 #### ENABLING BASH COMMAND SUBSTITUTION ####
 
-To enable support for arguments containing bash command substitions, 
+To enable support for arguments containing bash command substitutions, 
 you must do two things:
 
    1.  Enable arguments as described above

sample-config/nrpe.cfg.in

@@ -115,7 +115,7 @@ dont_blame_nrpe=0
 
 
 
-# BASH COMMAND SUBTITUTION
+# BASH COMMAND SUBSTITUTION
 # This option determines whether or not the NRPE daemon will allow clients
 # to specify arguments that contain bash command substitutions of the form
 # $(...).  This option only works if the daemon was configured with both