nixpkgs docs: Point to pkgs.extend, pkgs.appendOverlays and improve override section

1 files changed, 7 insertions, 1 deletions

diff --git a/doc/overlays.xml b/doc/overlays.xml
index 2decf9febe80..af1ab26b5e97 100644
--- a/doc/overlays.xml
+++ b/doc/overlays.xml
@@ -30,10 +30,16 @@
       itself is given, then that is used.
      </para>
      <para>
-      This can be passed explicitly when importing nipxkgs, for example
+      This can be passed explicitly when importing nixpkgs, for example
       <literal>import &lt;nixpkgs> { overlays = [ overlay1 overlay2 ];
       }</literal>.
      </para>
+     <para>
+      Further overlays can be added by calling the
+      <literal>pkgs.extend</literal> or <literal>pkgs.appendOverlays</literal>,
+      although it is often preferable to avoid these functions, because they
+      recompute the Nixpkgs fixpoint, which is somewhat expensive to do.
+     </para>
     </listitem>
     <listitem>
      <para>