docs: scaffold out shared-schemas re: #14082

Author: vkarpov15

docs/guides.md

@@ -25,6 +25,7 @@ integrating Mongoose with external tools and frameworks.
 
 ## Advanced Topics
 
+* [Sharing Schemas Between Mongoose Projects](shared-schemas.html)
 * [Working with Dates](tutorials/dates.html)
 * [Custom Casting For Built-in Types](tutorials/custom-casting.html)
 * [Custom SchemaTypes](customschematypes.html)

docs/shared-schemas.md

@@ -0,0 +1 @@
+# Sharing Schemas Between Mongoose Projects

docs/source/index.js

@@ -80,6 +80,7 @@ docs['docs/compatibility.md'] = {
   guide: true,
   markdown: true
 };
+docs['docs/shared-schemas.md'] = { guide: true, title: 'Sharing Schemas Between Mongoose Projects', markdown: true };
 docs['docs/field-level-encryption.md'] = { guide: true, title: 'Field Level Encryption', markdown: true };
 docs['docs/timestamps.md'] = { title: 'Mongoose Timestamps', markdown: true };
 docs['docs/search.pug'] = { title: 'Search' };