Add new builtin method for log rotation (#251)

Issues: syslog-ng/syslog-ng#5541

## The problem

Recently, starting with syslog-ng OSE version *4.10* file destinations
acquired new option: `logrotate()`. This PR does three things:
- inserts `logrotate()` option usage first in enumeration of log rotate
approaches
- adds link to log rotation page in the relevant place
- fixes typos in top-level **README**.

@HofiOne, in the original issue you mentioned:

> usage of external logrotators with reload/restart

Which I find a bit confusing because I thought that adding `REOPEN`
command was done just to avoid reloading/restarting syslog-ng. If I'm
wrong here and `syslog-ng-ctl reopen` cannot be used instead of
reload/restart, I will remove relevant change in this PR.

Author: HofiOne

README.md

@@ -14,7 +14,7 @@ This repository part contains the source code of `The syslog-ng OSE Administrati
 
 ## [Developer guide](https://syslog-ng.github.io/dev-guide/README)
 
-Do you like adding your idea, bug-fix to the fabolous syslog-ng? Help others to do the same, share your knwowledge in the [developer guide](https://syslog-ng.github.io/dev-guide/README).
+Do you like adding your idea, bug-fix to the fabulous syslog-ng? Help others to do the same, share your knowledge in the [developer guide](https://syslog-ng.github.io/dev-guide/README).
 
 ## [Generated document](https://syslog-ng.github.io/)
 

doc/_admin-guide/070_Destinations/040_File/README.md

@@ -45,7 +45,7 @@ destination d_file {
 
 **NOTE:** When using this destination, update the configuration of your log
 rotation program to rotate these files. Otherwise, the log files can
-become very large.
+become very large. See Configuring log rotation for available options.
 {: .notice--info}
 
 Also, after rotating the log files, reload {{ site.product.short_name }} using the

doc/_admin-guide/180_Best_practices_and_examples/004_Configuring_log_rotation.md

@@ -2,11 +2,32 @@
 title: Configuring log rotation
 id: adm-pract-rotate
 description: >- 
-    The {{ site.product.short_name }} application does not rotate logs by itself. This chapter
-    describes how to use {{ site.product.short_name }} for log rotation.
+    This chapter describes how to use {{ site.product.short_name }} for log rotation, making use of builtin options
+    and external tools.
 ---
 
-Consider the following approaches:
+Log rotation is traditionally only applicable to files and, consequently,
+to file destination drivers in {{ site.product.short_name }}. Consider the following approaches:
+
+## Use builtin logrotate() option of file destination driver
+
+- It is available starting with {{ site.product.short_name }} version 4.10 or later.
+
+- It is performed based on file sizes.
+
+- No additional configuration files are required - log rotation is configured
+    with the rest of {{ site.product.short_name }}. For details, see file() destination options.
+
+## Separate incoming logs based on time, host or other information
+
+- It is ideal for central log servers, where regular restart of
+    {{ site.product.short_name }} is unfavorable.
+
+- Requires shell scripts or cron jobs to remove old logs.
+
+- It can be done by using macros in the destination name (in the
+    filename, directory name, or the database table name). (For details
+    on using macros, see Templates and macros)
 
 ## Use logrotate together with {{ site.product.short_name }}
 
@@ -17,26 +38,17 @@ Consider the following approaches:
 - Less scripting is required, only logrotate has to be configured
     correctly.
 
-- Requires frequent restart ({{ site.product.short_name }} must be reloaded/restarted
-    when the files are rotated). After rotating the log files, reload
+- Starting from {{ site.product.short_name }} version 3.13 or later **syslog-ng-ctl reopen**
+    must be used to signal file destination drivers to open log files again without stopping
+    or interrupting the rest of configured log pipes. Alternately, {{ site.product.short_name }} can
+    be reloaded/restarted when the files are rotated. After rotating the log files, reload
     {{ site.product.short_name }} using the **syslog-ng-ctl reload** command, or use
-    another method to send a SIGHUP to {{ site.product.short_name }}.
+    another method to send a SIGHUP to {{ site.product.short_name }}
 
 - The statistics collected by {{ site.product.short_name }}, and the correlation
     information gathered with Pattern Database, are lost with each
     restart.
 
-## Separate incoming logs based on time, host or other information
-
-- It is ideal for central log servers, where regular restart of
-    {{ site.product.short_name }} is unfavorable.
-
-- Requires shell scripts or cron jobs to remove old logs.
-
-- It can be done by using macros in the destination name (in the
-    filename, directory name, or the database table name). (For details
-    on using macros, see Templates and macros
-
 ### Example: File destination for log rotation
 
 This sample file destination configuration stores incoming logs in files