Change docs to clarify which type of backup it's talking about

Change mentions of "incremental backup" in the docs to explicitly tell
which type of backup it's talking about i.e. block-level or file-level.

References: BAR-283

Signed-off-by: Gustavo William <gustavo.oliveira@enterprisedb.com>

doc/manual/43-backup-commands.en.md

@@ -82,17 +82,17 @@ barman keep <server_name> <backup_id> [--target TARGET, --status, --release]
 ```
 
 > **NOTE:**
-> To ensure the integrity of your backup system, incremental backups
+> To ensure the integrity of your backup system, block-level incremental backups
 > cannot use the keep annotation in Barman. This restriction is due to
-> the way incremental backups depend on each other. Using the keep 
-> annotation with incremental backups could result in orphaned backups,
+> the way block-level incremental backups depend on each other. Using the keep 
+> annotation on such backups could result in orphaned backups,
 > which means that certain backups might exist without their necessary
 > parent backups.
 >
 > In simpler terms, if you were allowed to apply the keep annotation to
-> an incremental backup, there would be a risk that parts of the backup
+> a block-level incremental backup, there would be a risk that parts of the backup
 > chain would be retained without their required predecessors. This 
-> situation could create backups that would be no longer useful or
+> situation could create backups that would be no longer be useful or
 > complete, as they would be missing the essential parent backups needed
 > to restore them properly.
 
@@ -374,9 +374,9 @@ the `--recovery-staging-path` option with the `barman recover` command. If
 you do neither of these things and attempt to recover a compressed backup
 then Barman will fail rather than try to guess a suitable location.
 
-### Recovering incremental backups
+### Recovering block-level incremental backups
 
-If a backup is incremental, `barman recover` is able to combine the chain
+If a backup is a block-level incremental, `barman recover` is able to combine the chain
 of backups on recovery through `pg_combinebackup`.
 A chain of backups is the tree branch that goes from the full backup
 to the one requested for the recovery. This is a multi-step process:
@@ -393,10 +393,10 @@ to the one requested for the recovery. This is a multi-step process:
     was created inside the provided staging directory, is removed at the end of the
     recovery process.
 
-When recovering from an incremental backup, you *must* therefore
+When recovering from a block-level incremental backup, you *must* therefore
 either set `local_staging_path` in the global/server config *or* use
 the `--local-staging-path` option with the `barman recover` command. If
-you do neither of these things and attempt to recover an incremental backup
+you do neither of these things and attempt to recover such backup
 then Barman fails rather than trying to guess a suitable location.
 
 > **IMPORTANT:**

doc/manual/50-feature-details.en.md

@@ -112,9 +112,9 @@ To be able to perform a block-level incremental backup in Barman you must:
 - Have `summarize_wal` enabled.
 - Have `postgres` as your backup method.
 
-> **NOTE:** Compressed backups are not **yet** eligible for incremental backups in Barman.
+> **NOTE:** Compressed backups are not **yet** eligible for block-level incremental backups in Barman.
 
-> **IMPORTANT:** If you decide to enable `data_checksums` between incremental backups,
+> **IMPORTANT:** If you decide to enable `data_checksums` between block-level incremental backups,
 > it is adivised to take a new full-backup as divergent checkum configurations can potentially
 > lead to issues during recovery.
 
@@ -594,12 +594,12 @@ Retention policy based on recovery window
 >
 > How It Works
 >
-> When the retention policy is applied, Barman ignores incremental backups
+> When the retention policy is applied, Barman ignores block-level incremental backups
 > and focuses only on the status of the full backups.
 >
 > If the full backup is marked as KEEP:FULL, KEEP:STANDALONE, or VALID,
-> the status VALID is marked to all dependent incremental backups.
-> If the full backup is marked as OBSOLETE, then all incremental backups
+> the status VALID is marked to all dependent block-level incremental backups.
+> If the full backup is marked as OBSOLETE, then all block-level incremental backups
 > that depend on it will also be marked as OBSOLETE and removed.
 
 #### Scope