Documentation and Readme update about versioning

Author: gsmolk

Documentation.md

@@ -6,6 +6,7 @@ Current version - 2.1.3
 
 1. [Synopsis](#synopsis)
 2. [Overview](#overview)
+    * [Versioning](#versioning)
     * [Limitations](#limitations)
 
 3. [Installation and Setup](#installation-and-setup)
@@ -134,12 +135,16 @@ pg_probackup can take only physical online backups, and online backups require W
 - ARCHIVE. Such backups rely on [continuous archiving](#setting-up-continuous-wal-archiving) to ensure consistent recovery. This is the default WAL delivery method.
 - STREAM. Such backups include all the files required to restore the cluster to a consistent state at the time the backup was taken. Regardless of [continuous archiving](#setting-up-continuous-wal-archiving) been set up or not, the WAL segments required for consistent recovery are streamed (hence STREAM) via replication protocol during backup and included into the backup files.
 
+### Versioning
+
+pg_probackup is following [semantic](https://semver.org/) versioning.
+
 ### Limitations
 
 pg_probackup currently has the following limitations:
 
 - Creating backups from a remote server is currently not supported on Windows systems.
-- The PostgreSQL server from which the backup was taken and the restored server must be compatible by the [block_size](https://www.postgresql.org/docs/current/runtime-config-preset.html#GUC-BLOCK-SIZE) and [wal_block_size](https://www.postgresql.org/docs/current/runtime-config-preset.html#GUC-WAL-BLOCK-SIZE) parameters and have the same major release number. 
+- The PostgreSQL server from which the backup was taken and the restored server must be compatible by the [block_size](https://www.postgresql.org/docs/current/runtime-config-preset.html#GUC-BLOCK-SIZE) and [wal_block_size](https://www.postgresql.org/docs/current/runtime-config-preset.html#GUC-WAL-BLOCK-SIZE) parameters and have the same major release number.
 
 ## Installation and Setup
 

README.md

@@ -45,6 +45,10 @@ Regardless of the chosen backup type, all backups taken with `pg_probackup` supp
 * Remote mode is in beta stage.
 * Incremental chain can span only within one timeline. So if you have backup incremental chain taken from replica and it gets promoted, you would be forced to take another FULL backup.
 
+## Current release
+
+[2.1.3](https://github.com/postgrespro/pg_probackup/releases/tag/2.1.3)
+
 ## Installation and Setup
 ### Windows Installation
 [Installers download link](https://oc.postgrespro.ru/index.php/s/CGsjXlc5NmhRI0L)
@@ -81,7 +85,7 @@ yum install pg_probackup-{11,10,9.6,9.5}-debuginfo
 yumdownloader --source pg_probackup-{11,10,9.6,9.5}
 ```
 
-Once you have `pg_probackup` installed, complete [the setup](https://postgrespro.com/docs/postgrespro/current/app-pgprobackup.html#pg-probackup-install-and-setup).
+Once you have `pg_probackup` installed, complete [the setup](https://github.com/postgrespro/pg_probackup/blob/master/Documentation.md#installation-and-setup).
 
 ## Building from source
 ### Linux
@@ -104,10 +108,6 @@ SET PATH=%PATH%;C:\msys64\usr\bin
 gen_probackup_project.pl C:\path_to_postgresql_source_tree
 ```
 
-## Current release
-
-[2.1.3](https://github.com/postgrespro/pg_probackup/releases/tag/2.1.3)
-
 ## Documentation
 
 Currently the latest documentation can be found at [github](https://github.com/postgrespro/pg_probackup/blob/master/Documentation.md) and [Postgres Pro Enterprise documentation](https://postgrespro.com/docs/postgrespro/current/app-pgprobackup).