Remove section on why the feature should be stabilized

We already documented that this needs to go through FCP before making a PR.

Co-authored-by: Mara Bos <[email protected]>

Author: jyn514

src/stability.md

@@ -81,8 +81,7 @@ To stabilize a feature, follow these steps:
    compiler or tools, remove it from there as well.
 3. If applicable, change `#[rustc_const_unstable]` to `#[rustc_const_stable(since = "version")]`.
 4. Open a PR against `rust-lang/rust`
-   - Add the appropriate labels: `@rustbot modify labels: +T-libs +needs-fcp`.
-   - Include a description of the feature and why it should be stabilized.
+   - Add the appropriate labels: `@rustbot modify labels: +T-libs`.
    - Link to the tracking issue and say "Closes #XXXXX".
 
 You can see an example of stabilizing a feature at [#75132](https://github.com/rust-lang/rust/pull/75132).