doc: Fix description of the JIT time fields in pg_stat_statements

The four fields tracking the time spent by queries for JIT operations
added in 57d6aea were listed as having bigint as data type, but these
are of type double precision.

Author: Noriyoshi Shinoda
Reviewed-by: Nathan Bossart
Discussion: https://postgr.es/m/DM4PR84MB1734375E63148AADC6A1E6B4EED39@DM4PR84MB1734.NAMPRD84.PROD.OUTLOOK.COM

Author: michaelpq

doc/src/sgml/pgstatstatements.sgml

@@ -413,7 +413,7 @@
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-       <structfield>jit_generation_time</structfield> <type>bigint</type>
+       <structfield>jit_generation_time</structfield> <type>double precision</type>
       </para>
       <para>
        Total time spent by the statement on generating JIT code, in milliseconds
@@ -431,7 +431,7 @@
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-       <structfield>jit_inlining_time</structfield> <type>bigint</type>
+       <structfield>jit_inlining_time</structfield> <type>double precision</type>
       </para>
       <para>
        Total time spent by the statement on inlining functions, in milliseconds
@@ -449,7 +449,7 @@
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-       <structfield>jit_optimization_time</structfield> <type>bigint</type>
+       <structfield>jit_optimization_time</structfield> <type>double precision</type>
       </para>
       <para>
        Total time spent by the statement on optimizing, in milliseconds
@@ -467,7 +467,7 @@
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-       <structfield>jit_emission_time</structfield> <type>bigint</type>
+       <structfield>jit_emission_time</structfield> <type>double precision</type>
       </para>
       <para>
        Total time spent by the statement on emitting code, in milliseconds