[docs] formatting and general pedantry

I'm not sure if the `distance-units` section is totally clear, when using the 'Geohash Cell Filter' and omitting a unit, the default is to interpret the integer as the 'length of the geohash prefix', not to default it to 'meter'. Maybe I'm being pedantic.

Closes #8744

docs/reference/api-conventions.asciidoc

@@ -48,9 +48,9 @@ to. If `open` is specified then the wildcard expression is expanded to only
 open indices and if `closed` is specified then the wildcard expression is
 expanded only to closed indices. Also both values (`open,closed`) can be
 specified to expand to all indices.
-+
-If `none` is specified then wildcard expansion will be disabled and if `all` 
-is specified, wildcard expressions will expand to all indices (this is equivalent 
+
+If `none` is specified then wildcard expansion will be disabled and if `all`
+is specified, wildcard expressions will expand to all indices (this is equivalent
 to specifying `open,closed`).
 
 The defaults settings for the above parameters depend on the api being used.
@@ -68,7 +68,7 @@ The following options can be applied to all of the REST APIs.
 
 When appending `?pretty=true` to any request made, the JSON returned
 will be pretty formatted (use it for debugging only!). Another option is
-to set `format=yaml` which will cause the result to be returned in the
+to set `?format=yaml` which will cause the result to be returned in the
 (sometimes) more readable yaml format.
 
 
@@ -77,7 +77,7 @@ to set `format=yaml` which will cause the result to be returned in the
 
 Statistics are returned in a format suitable for humans
 (eg `"exists_time": "1h"` or `"size": "1kb"`) and for computers
-(eg `"exists_time_in_millis": 3600000`` or `"size_in_bytes": 1024`).
+(eg `"exists_time_in_millis": 3600000` or `"size_in_bytes": 1024`).
 The human readable values can be turned off by adding `?human=false`
 to the query string. This makes sense when the stats results are
 being consumed by a monitoring tool, rather than intended for human
@@ -88,7 +88,7 @@ consumption.  The default for the `human` flag is
 === Flat Settings
 
 The `flat_settings` flag affects rendering of the lists of settings. When
-flat_settings` flag is `true` settings are returned in a flat format:
+`flat_settings` flag is `true` settings are returned in a flat format:
 
 [source,js]
 --------------------------------------------------
@@ -160,8 +160,7 @@ can be specified as a whole number representing time in milliseconds, or as a ti
 === Distance Units
 
 Wherever distances need to be specified, such as the `distance` parameter in
-the <<query-dsl-geo-distance-filter>>) or the `precision` parameter in the
-<<query-dsl-geohash-cell-filter>>, the default unit if none is specified is
+the <<query-dsl-geo-distance-filter>>), the default unit if none is specified is
 the meter. Distances can be specified in other units, such as `"1km"` or
 `"2mi"` (2 miles).
 
@@ -178,6 +177,10 @@ Centimeter::    `cm` or `centimeters`
 Millimeter::    `mm` or `millimeters`
 Nautical mile:: `NM`, `nmi` or `nauticalmiles`
 
+The `precision` parameter in the <<query-dsl-geohash-cell-filter>> accepts
+distances with the above units, but if no unit is specified, then the
+precision is interpreted as the length of the geohash.
+
 [[fuzziness]]
 [float]
 === Fuzziness