doc: Fix formatting

openstackdocstheme shows vertical lines for quote blocks.
This commit removes unnecessary leading spaces.

Change-Id: Ie5651f0510550eb3910e68e433a41e99bf2bfa8a

doc/source/user/collectors.rst

@@ -4,36 +4,37 @@ Collectors
 
 There are a number of drivers to support different collector backends:
 
-Redis:
-------
+Redis
+-----
+
 * Overview
+
   The Redis driver allows profiling data to be collected into a redis
   database instance. The traces are stored as key-value pairs where the
   key is a string built using trace ids and timestamps and the values
   are JSON strings containing the trace information. A second driver is
   included to use Redis Sentinel in addition to single node Redis.
 
-  * Capabilities:
-        * Write trace data to the database.
+* Capabilities
 
+  * Write trace data to the database.
   * Query Traces in database: This allows for pulling trace data
     querying on the keys used to save the data in the database.
-
   * Generate a report based on the traces stored in the database.
-
   * Supports use of Redis Sentinel for robustness.
 
-  * Usage:
+* Usage
+
   The driver is used by OSProfiler when using a connection-string URL
   of the form redis://<hostname>:<port>. To use the Sentinel version
   use a connection-string of the form redissentinel://<hostname>:<port>
 
-  * Configuration:
-        * No config changes are required by for the base Redis driver.
+* Configuration
 
+  * No config changes are required by for the base Redis driver.
   * There are two configuration options for the Redis Sentinel driver:
+
     * socket_timeout: specifies the sentinel connection socket timeout
       value. Defaults to: 0.1 seconds
-
     * sentinel_service_name: The name of the Sentinel service to use.
       Defaults to: "mymaster"