Added Intros for REST API Pages (#8371)

Co-authored-by: Sarah Edwards <skedwards88@github.com>

content/rest/reference/git.md

@@ -1,5 +1,6 @@
 ---
 title: Git database
+intro: 'The Git Database API enables you to read and write raw Git objects to your Git database on {% data variables.product.product_name %} and to list and update Git references (branch heads and tags).'
 allowTitleToDifferFromFilename: true
 redirect_from:
   - /v3/git

content/rest/reference/gitignore.md

@@ -1,5 +1,6 @@
 ---
 title: Gitignore
+intro: "The Gitignore API fetches `.gitignore` templates that can be used to ignore files and directories."
 redirect_from:
   - /v3/gitignore
 versions:

content/rest/reference/interactions.md

@@ -1,5 +1,6 @@
 ---
 title: Interactions
+intro: 'With the Interactions API, people with owner or admin access can set the interaction limit for the users in their organizations and repositories.'
 redirect_from:
   - /v3/interactions
 versions:

content/rest/reference/issues.md

@@ -1,5 +1,6 @@
 ---
 title: Issues
+intro: 'The Issues API enables you to view and manage issues, including issue assignees, comments, labels, and milestones.'
 redirect_from:
   - /v3/issues
 versions:

content/rest/reference/licenses.md

@@ -1,5 +1,6 @@
 ---
 title: Licenses
+intro: "The Licenses API lets you to retrieve popular open source licenses and information about a particular project's license file."
 redirect_from:
   - /v3/licenses
 versions: