[docs] Add sources policy (#3902)

* Add sources policy

* Update docs/README.md

Co-authored-by: Yoann Potinet <intelligide@hotmail.fr>

* Update docs/packaging_policy.md

Co-authored-by: Anonymous Maarten <madebr@users.noreply.github.com>

* Update docs/packaging_policy.md

Co-authored-by: Chris Mc <prince.chrismc@gmail.com>

* Review

* Update docs/packaging_policy.md

Co-authored-by: SSE4 <tomskside@gmail.com>

Co-authored-by: Yoann Potinet <intelligide@hotmail.fr>
Co-authored-by: Anonymous Maarten <madebr@users.noreply.github.com>
Co-authored-by: Chris Mc <prince.chrismc@gmail.com>
Co-authored-by: SSE4 <tomskside@gmail.com>

docs/README.md

@@ -8,7 +8,7 @@
 * User documentation
   + [Contributing to Conan Center Index](contributing.md)
   + [Adding Packages to ConanCenter](how_to_add_packages.md)
+  + [Packaging policy](packaging_policy.md)
   + [Supported platforms and configurations](supported_platforms_and_configurations.md)
   + [Errors from the conan-center hook (KB-Hxxx)](error_knowledge_base.md)
   + [FAQs](faqs.md)
-

docs/packaging_policy.md

@@ -0,0 +1,22 @@
+# Packaging Policy
+
+This document gathers all the relevant information regarding the general lines to follow while creating new recipes that will eventually be
+part of this repository.
+
+## Sources
+
+**Origin of sources:** Library sources should come from an official origin like the library source code repository or the official
+release/download webpage.
+
+**Building from sources:** Recipes should always build packages from library sources.
+
+**Sources not accessible:**
+
+- Library sources that are not publicly available will not be allowed in this repository even if the license allows their redistribution.
+
+- If library sources cannot be downloaded from their official origin or cannot be consumed directly due to their
+  format, the recommendation is to contact the publisher and ask them to provide the sources in a way/format that can be consumed
+  programmatically.
+
+- In case of needing those binaries to use them as a "build require" for some library, we will consider following the approach of adding it
+  as a system recipe (`<build_require>/system`) and making those binaries available in the CI machines (if the license allows it).