fix: Add doc on validation

docs/validation.md

@@ -0,0 +1,46 @@
+# Validation
+
+Validation is the final step of the mapping process. It is necessary
+to ensure good quality data. Validation requires a slightly different
+skill set than just being a good mapper. Being an experienced mapper is
+a good start of course. 
+
+For Tasking Manager, validators review the work of the remote
+mappers. It is not unusual that features get misidentified by the
+mappers due to poor imagery. Validators have much experience with
+identifying obscure buildings types in different countries.
+
+Being a validator is more than being a mapper. As a person dealing
+with quality issues, a validator is also a mentor to other mappers,
+improving their skills as well. Mentoring of course requires an
+ability to communicate mistakes with empathy and understanding, as we
+all make mistakes... 
+
+## References
+
+There are multiple good sources for information on validation for more detail.
+
+* After you’ve had some experience mapping, you may find yourself
+correcting other contributors work. [/MissingMaps_validation_faq_en.pdf](https://www.missingmaps.org/assets/downloads/MissingMaps_validation_faq_en.pdf)
+
+* Before validating the work of others, you should be an experienced
+  mapper yourself. [Validating_Data_EN.pdf](https://www.missingmaps.org/assets/downloads/Validating_Data_EN.pdf)
+
+* Mappers wishing to become validators should take time to become
+  experienced at mapping and learn what validation entails before
+  submitting an application. [validators-experienced-mappers-making-an-outsized-difference/](https://www.hotosm.org/updates/validators-experienced-mappers-making-an-outsized-difference/)
+
+* Validation is the process of an experienced mapper reviewing the
+  mapping of the initial mapper of a project task. [Validation](https://learnosm.org/en/coordination/validation/)
+
+* In OpenStreetMap anyone can validate as long as they do not validate
+  their own work. However, they can validate another mapper's
+  contributions. [Validating Data](https://wiki.openstreetmap.org/wiki/Tasking_Manager/Validating_data)
+
+* Mappers that wish to become validators must have experience with
+  tracing and tagging complex features in OSM, outstanding image
+  interpretation skills, a positive attitude and manner towards other
+  users, and a willingness to learn new software. [Validation
+  hub](https://www.youthmappers.org/validation-hub)
+
+

mkdocs.yml

@@ -88,5 +88,6 @@ nav:
       - Customize: sysadmins/customize.md
       - CI: sysadmins/ci-cd.md
   - Working Groups: working-groups.md
+  - Validation: validation.md
   - License: LICENSE.md
 #  - Changelog: CHANGELOG.md