filter: lua: fix markdown formatting (fluent#142)

Signed-off-by: ialidzhikov <i.alidjikov@gmail.com>

filter/lua.md

@@ -59,7 +59,7 @@ In your main configuration file append the following _Input_, _Filter_ & _Output
 The life cycle of a filter have the following steps:
 
 * Upon Tag matching by filter\_lua, it may process or bypass the record.
-* If filter_lua accepts the record, it will invoke the function defined in the \_call_ property which basically is the name of a function defined in the Lua _script_.
+* If filter\_lua accepts the record, it will invoke the function defined in the _call_ property which basically is the name of a function defined in the Lua _script_.
 * Invoke Lua function passing each record in JSON format.
 * Upon return, validate return value and take some action \(described above\)
 
@@ -87,7 +87,7 @@ Each callback **must** return three values:
 
 | name | data type | description |
 | :--- | :--- | :--- |
-| code | integer | The code return value represents the result and further action that may follows. If _code_ equals -1, means that filter_lua must drop the record. If \_code_ equals 0 the record will not be modified, otherwise if _code_ equals 1, means the original timestamp or record have been modified so it must be replaced by the returned values from _timestamp_ \(second return value\) and _record_ \(third return value\). |
+| code | integer | The code return value represents the result and further action that may follows. If _code_ equals -1, means that filter\_lua must drop the record. If _code_ equals 0 the record will not be modified, otherwise if _code_ equals 1, means the original timestamp or record have been modified so it must be replaced by the returned values from _timestamp_ \(second return value\) and _record_ \(third return value\). |
 | timestamp | double | If code equals 1, the original record timestamp will be replaced with this new value. |
 | record | table | if code equals 1, the original record information will be replaced with this new value. Note that the format of this value **must** be a valid Lua table. |