Clean up variable names, remove broken objects, prettify queries, add pagination example

[sn2b]

Following the addition of some new queries, I tried to standardize them a little bit. This includes the following:

• Using standard variable and value names (camelcase for variables like orgName, uppercase for value placeholders like ORG_NAME)
• Making sure every query starts with query {
• Renaming graphql/queries/10-mutation-issue-comment-get-issue.graphql to reflect that it is a query, not a mutation
• Adding a query that demonstrates pagination with the gh cli

Let me know if you are not happy with these changes. Happy to discuss!