Update bash-extracting_from_files.md

docs/pages/bash/bash-extracting_from_files.md

@@ -35,6 +35,8 @@ Using commands `head` and `tail` allows to do this tasks.
 
 ## Searching patterns (grep)
 
+## Replacing patterns (sed)
+
 ## Redirecting an output (>)
 
 ## Combining commands (| && ;)