Rename syntax definitions

Duplicate syntax definition names may cause problems.
Since nano comes with predefined all-lowercase syntax definitions,
we use uppercase letters everywhere to reduce the risk of future conflicts

man.nanorc

@@ -1,6 +1,6 @@
 ## Here is an example for manpages.
 ##
-syntax "man" "\.[1-9]x?$"
+syntax "Man" "\.[1-9]x?$"
 color green "\.(S|T)H.*$"
 color brightgreen "\.(S|T)H" "\.TP"
 color brightred "\.(BR?|I[PR]?).*$"