add PR number

Author: Intron7

docs/release-notes/0.15.1.md

@@ -8,7 +8,7 @@
 ```{rubric} Bug fixes
 ```
 * Fixes `tl.rank_genes_groups` returning NaN/zero `logfoldchanges`/`pvals` with `groups=[subset]` and `reference='rest'` {pr}`651` {smaller}`S Dicks`
-* Fixes float64 precision loss in the sparse Pearson-residual kernels: ``pp.normalize_pearson_residuals`` (and ``pp.highly_variable_genes`` with ``flavor='pearson_residuals'``) on CSR/CSC input divided by the single-precision intrinsic ``sqrtf``, silently capping the float64 path at ~7 significant digits {pr}`xxx` {smaller}`A Mikaeili`
+* Fixes float64 precision loss in the sparse Pearson-residual kernels: ``pp.normalize_pearson_residuals`` (and ``pp.highly_variable_genes`` with ``flavor='pearson_residuals'``) on CSR/CSC input divided by the single-precision intrinsic ``sqrtf``, silently capping the float64 path at ~7 significant digits {pr}`658` {smaller}`A Mikaeili`
 
 ```{rubric} Misc
 ```