fix typos in pull request template
fix typos in pull request template

jenkinsci/jenkins-design-language,alvarolobato/blueocean-plugin,alvarolobato/blueocean-plugin,kzantow/blueocean-plugin,jenkinsci/jenkins-design-language,jenkinsci/blueocean-plugin,jenkinsci/blueocean-plugin,jenkinsci/blueocean-plugin,jenkinsci/blueocean-plugin,kzantow/blueocean-plugin,kzantow/blueocean-plugin,alvarolobato/blueocean-plugin,alvarolobato/blueocean-plugin,jenkinsci/blueocean-plugin,kzantow/blueocean-plugin