Update maxRequestBodySize default to medium (#12728)

This option is set to `medium` by default in (almost) all of the SDKs

Author: lcian

develop-docs/sdk/expected-features/index.mdx

@@ -538,9 +538,9 @@ Ability for the SDK to attach request body to events and triggered during the ex
 User should be able to set a configuration option `maxRequestBodySize` to instruct SDK how big requests bodies should be attached.
 SDK controls what is an actual size in bytes for each option:
 
-- `none` (default)
+- `none`
 - `small` - `1000` bytes
-- `medium` - `10000` bytes
+- `medium` - `10000` bytes (default)
 - `always`
 
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