Fixes Canvas doc headers (#40921)

docs/canvas/canvas-function-reference.asciidoc

@@ -1,6 +1,6 @@
 [role="xpack"]
 [[canvas-function-reference]]
-= Canvas function reference
+== Canvas function reference
 
 Behind the scenes, Canvas is driven by a powerful expression language,
 with dozens of functions and other capabilities, including table transforms, 
@@ -18,6 +18,8 @@ A *†* denotes an argument can be passed multiple times.
 [float]
 [[a_fns]]
 == A
+
+[float]
 [[all_fn]]
 === `all`
 
@@ -179,6 +181,8 @@ Default: `true`
 [float]
 [[c_fns]]
 == C
+
+[float]
 [[case_fn]]
 === `case`
 
@@ -379,6 +383,8 @@ Alias: `data`
 [float]
 [[d_fns]]
 == D
+
+[float]
 [[date_fn]]
 === `date`
 
@@ -483,6 +489,8 @@ Configures a dropdown filter control element.
 [float]
 [[e_fns]]
 == E
+
+[float]
 [[eq_fn]]
 === `eq`
 
@@ -649,6 +657,8 @@ capitalization.
 [float]
 [[f_fns]]
 == F
+
+[float]
 [[filterrows_fn]]
 === `filterrows`
 
@@ -812,6 +822,8 @@ Alias: `format`
 [float]
 [[g_fns]]
 == G
+
+[float]
 [[getCell_fn]]
 === `getCell`
 
@@ -888,6 +900,8 @@ Alias: `value`
 [float]
 [[h_fns]]
 == H
+
+[float]
 [[head_fn]]
 === `head`
 
@@ -914,6 +928,8 @@ Default: `1`
 [float]
 [[i_fns]]
 == I
+
+[float]
 [[if_fn]]
 === `if`
 
@@ -984,6 +1000,8 @@ data:image/svg+xml;`base64`,PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiIHN0
 [[j_fns]]
 == J
 
+[float]
+
 [float]
 [[joinRows_fn]]
 === `joinRows`
@@ -1029,6 +1047,8 @@ Default: `", "`
 [float]
 [[l_fns]]
 == L
+
+[float]
 [float]
 [[location_fn]]
 === `location`
@@ -1088,6 +1108,8 @@ Alias: `value`
 [float]
 [[m_fns]]
 == M
+
+[float]
 [[mapColumn_fn]]
 === `mapColumn`
 
@@ -1206,6 +1228,8 @@ Default: `{<<font_fn>> size=14 family="'Open Sans', Helvetica, Arial, sans-serif
 [float]
 [[n_fns]]
 == N
+
+[float]
 [[neq_fn]]
 === `neq`
 
@@ -1230,6 +1254,8 @@ Alias: `value`
 [float]
 [[p_fns]]
 == P
+
+[float]
 [[palette_fn]]
 === `palette`
 
@@ -1519,6 +1545,8 @@ Default: `20`
 [float]
 [[r_fns]]
 == R
+
+[float]
 [[render_fn]]
 === `render`
 
@@ -1707,6 +1735,8 @@ Returns the number of rows. Pairs with `<<ply_fn>>` to get the count of unique c
 [float]
 [[s_fns]]
 == S
+
+[float]
 [[seriesStyle_fn]]
 === `seriesStyle`
 
@@ -1917,6 +1947,8 @@ Alias: `finally`
 [float]
 [[t_fns]]
 == T
+
+[float]
 [[table_fn]]
 === `table`
 
@@ -2126,6 +2158,8 @@ Alias: `type`
 [float]
 [[u_fns]]
 == U
+
+[float]
 [[urlparam_fn]]
 === `urlparam`