docs(development): guide to create/edit presets

docs/development/creating-editing-renovate-presets.md

@@ -0,0 +1,38 @@
+# Creating/editing Renovate presets
+
+Renovate comes with default presets that you can find in the `lib/config/presets/internal` directory.
+You can suggest changes to the presets with a pull request.
+
+Follow the rules below to increase the chance that your pull request gets merged.
+
+## General rules
+
+1. Only create/edit presets for problems which can not be fixed upstream
+1. The internal preset must be helpful for most Renovate users
+
+### Specific rules
+
+#### Group presets
+
+File location: `lib/config/presets/internal/group.ts`
+
+Rules:
+
+1. Only group dependencies together that must be updated together
+
+#### Replacement presets
+
+File location: `lib/config/presets/internal/replacements.ts`
+
+Rules:
+
+1. Only suggest a replacement PR when the user is on the latest `major` release of the deprecated dependency, use the `matchCurrent` config option to control when the replacement PR is allowed
+1. No big version jumps, update to the first stable version of the replacement dependency
+
+#### Monorepo presets
+
+File location: `lib/config/presets/internal/monorepo.ts`
+
+Rules:
+
+1. First check if the problem can be fixed in the source monorepo itself, sometimes the monorepo is not configured properly