unity run editor function everytime I save a script

I have used a script which if placed in my 'Editor' folder adds creation date and time to my script. As a result I know exactly when my script was created.
I would like to write a editor script that runs on all my scripts and If I save a script during development, It should search for a variable (updateTime) and replace the date and time with my current date and time.
I send out scripts to others for integration and It is really hard to remember all scripts where i make minor changes after last send.

Any minor script to do this or how to achieve it is appreciated.

 

Instead of this approach, you might also/instead consider using source code control, like Github.

 

I have moved to git but I am curious now as to how to achieve it. Basically search a particular pattern like 'LastUpdated : 12/18/2018 3:57:41 PM' and edit it to 'LastUpdated : 12/18/2018 4:16:01 PM' or whatever is the current time.
I tried with 'OnWillSaveAssets(string path)' but there was no effect of this.

Also attaching the file and how I tried to code it along with my default Script Template.

 

You use Git commands to see when a file was last updated, never explicitly write date information