ci(dependencies): create history-substring-search files as expected

.github/dependencies.yml

@@ -24,4 +24,8 @@ dependencies:
     version: 8f5d8a5aa9942da7b2a764c7fa79e0f36ba802f7
     precopy: |
       set -e
-      test -e zsh-history-substring-search.plugin.zsh && mv zsh-history-substring-search.plugin.zsh history-substring-search.plugin.zsh
+      rm -f zsh-history-substring-search.plugin.zsh
+      test -e zsh-history-substring-search.zsh && mv zsh-history-substring-search.zsh history-substring-search.zsh
+    postcopy: |
+      set -e
+      test -e dependencies/OMZ-README.md && cat dependencies/OMZ-README.md >> README.md

plugins/history-substring-search/dependencies/OMZ-README.md

@@ -0,0 +1,19 @@
+
+---
+
+## Oh My Zsh Distribution Notes
+
+What you are looking at now is Oh My Zsh's repackaging of zsh-history-substring-search as an OMZ module inside
+the Oh My Zsh distribution.
+
+The upstream repo, zsh-users/zsh-history-substring-search, can be found on GitHub at
+https://github.com/zsh-users/zsh-history-substring-search.
+
+This downstream copy was last updated from the following upstream commit:
+
+SHA: 8dd05bfcc12b0cd1ee9ea64be725b3d9f713cf64 Commit date: 2023-11-23 12:12:14 +0200
+
+Everything above this section is a copy of the original upstream's README, so things may differ slightly when
+you're using this inside OMZ. In particular, you do not need to set up key bindings for the up and down arrows
+yourself in `~/.zshrc`; the OMZ plugin does that for you. You may still want to set up additional emacs- or
+vi-specific bindings as mentioned above.