Update fixed-precision docs to reflect constants parsed as DECIMAL
Update fixed-precision docs to reflect constants parsed as DECIMAL

Since 0.198 the default behavior is that decimal literals without an
explicit type specifier (e.g. 1.2) are treated as DECIMAL where
prior to 0.198 they were treated as DOUBLE.

PR: https://github.com/prestodb/presto/pull/13281

EvilMcJerkface/presto,ptkool/presto,mvp/presto,EvilMcJerkface/presto,ptkool/presto,ptkool/presto,mvp/presto,EvilMcJerkface/presto,mvp/presto,prestodb/presto,prestodb/presto,arhimondr/presto,twitter-forks/presto,twitter-forks/presto,facebook/presto,shixuan-fan/presto,facebook/presto,EvilMcJerkface/presto,ptkool/presto,facebook/presto,zzhao0/presto,prestodb/presto,zzhao0/presto,twitter-forks/presto,nezihyigitbasi/presto,shixuan-fan/presto,nezihyigitbasi/presto,mvp/presto,ptkool/presto,mvp/presto,nezihyigitbasi/presto,arhimondr/presto,shixuan-fan/presto,zzhao0/presto,arhimondr/presto,arhimondr/presto,EvilMcJerkface/presto,facebook/presto,arhimondr/presto,prestodb/presto,nezihyigitbasi/presto,twitter-forks/presto,facebook/presto,zzhao0/presto,shixuan-fan/presto,twitter-forks/presto,shixuan-fan/presto,zzhao0/presto,prestodb/presto,prestodb/presto,nezihyigitbasi/presto