Auto merge of #7600 - xFrednet:0000-update-issue-templates, r=camsteffen

Updated issue templates(formatting and rustbot label reference)

This PR updates our issue templates. The changes are:

1. **Make the *Meta* section smaller and not indented**

    The current format sometimes gets messed up when a user simply pasts the rustc version into the issue without indenting it to match the code block. Removing the indention should hopefully help with formatting in the future.

    <details><summary>Example of messed up formatting </summary>

    ![image](https://user-images.githubusercontent.com/17087237/130811809-2b9bc58e-c13f-4338-b34e-18648a5de413.png)

    </details>

    Additionally, I've removed the Version of Clippy from the template. Every issue that I have seen had matching rustc and Clippy versions, and just asking for `rustc -Vv` makes the issue look cleaner IMO.

2. **Add a comment explaining how additional labels can be added with ``@rustbot` label +<label>`. The explanation looks like this:**

    ```
    <!--
    Additional labels can be added to this issue by including the following command:

    `@rustbot` label +<label>

    Common labels for this issue type are:
    * `I-suggestion-causes-error`
    -->
    ```

    The example ``@rustbot`` call can sadly not be marked as code inside a comment block. But the example will not cause the bot to add any labels. See rust-lang/rust-clippy#7599

---

changelog: none

cc: `@rust-lang/clippy`

0 files changed, 0 insertions, 0 deletions