Generating Github Token & Updating It In Jenkins

Login to Github account
Go to setting
Under setting go to Developer settings:
Under Developer settings select Personal Access Token and click of Generate new token
Now give token name and select the admin:repo_hook permission and click on Generate token
And this will generate token for you, make a note of the token now.
Login to your Jenkins server and from Jenkins dashboard go to Manage Jenkins
Now click on Manage Credentials
Now click on Jenkins
Select Global credentials
Click on Add Credentials
Select
Kind: Username with password
Scope: Global
Username: Your Github username
Password: Personal Access token which was created in Step 6
ID: Github or anything as per your choice