docs: move place ranking into customization part

docs/customize/Ranking.md

@@ -1,8 +1,7 @@
 # Place Ranking in Nominatim
 
 Nominatim uses two metrics to rank a place: search rank and address rank.
-Both can be assigned a value between 0 and 30. They serve slightly
-different purposes, which are explained in this chapter.
+This chapter explains what place ranking means and how it can be customized.
 
 ## Search rank
 

docs/mkdocs.yml

@@ -27,6 +27,7 @@ pages:
         - 'Overview': 'customize/Overview.md'
         - 'Import Styles': 'customize/Import-Styles.md'
         - 'Configuration Settings': 'customize/Settings.md'
+        - 'Place Ranking' : 'customize/Ranking.md'
         - 'Tokenizers' : 'customize/Tokenizers.md'
         - 'Special Phrases': 'customize/Special-Phrases.md'
         - 'External data: US housenumbers from TIGER': 'customize/Tiger.md'
@@ -35,7 +36,6 @@ pages:
         - 'Setup for Development' : 'develop/Development-Environment.md'
         - 'Architecture Overview' : 'develop/overview.md'
         - 'OSM Data Import' : 'develop/Import.md'
-        - 'Place Ranking' : 'develop/Ranking.md'
         - 'Tokenizers' : 'develop/Tokenizers.md'
         - 'Postcodes' : 'develop/Postcodes.md'
         - 'Testing' : 'develop/Testing.md'