(feature): fixed typo. reported by Vale

Signed-off-by: Hasan Oezdemir <21654050+nodify-at@users.noreply.github.com>

.changeset/gold-garlics-sing.md

@@ -2,4 +2,4 @@
 '@backstage/plugin-jenkins-common': major
 ---
 
-Add a new common plugin for jenkins which provides shared isomorphic code for the jenkins plugin.
+Add a new common plugin for Jenkins which provides shared isomorphic code for the Jenkins plugin.

.changeset/orange-cobras-shave.md

@@ -2,5 +2,5 @@
 '@backstage/plugin-jenkins-backend': minor
 ---
 
-Add permissions support for jenkins backend and provide an integration router. You must pass a permission router
-if you want to enable permissions in jenkins plugin.
+Add permissions support for Jenkins backend and provide an integration router. You must pass a permission router
+if you want to enable permissions in Jenkins plugin.

plugins/jenkins-common/README.md

@@ -1,3 +1,3 @@
 # Jenkins Common
 
-Shared isomorphic code for the jenkins plugin.
+Shared isomorphic code for the Jenkins plugin.