Merge #13844: doc: correct the help output for -prune

312ff01 -prune option -help output aligned with code (Hennadii Stepanov)

Pull request description:

  The -help output for -prune is aligned with the code.

  In the code (.../src/init.cpp#L1063):
  ```
          if (nPruneTarget < MIN_DISK_SPACE_FOR_BLOCK_FILES) {
              return InitError(strprintf(_("Prune configured below the minimum of %d MiB.  Please use a higher number."), MIN_DISK_SPACE_FOR_BLOCK_FILES / 1024 / 1024));
          }
  ```
  So correct value of nPruneTarget is **greater than or equal to** MIN_DISK_SPACE_FOR_BLOCK_FILES.

Tree-SHA512: 8e55aa99c8f5a9d020677b0f1b016215e2dbda5fa4ee7c8504b12a3abef226bc21beca118fa332c0bf206a4aff913a5a717b55bb5b2ecdba38423e9c0161209e

Author: laanwj

src/init.cpp

@@ -382,7 +382,7 @@ void SetupServerArgs()
 #endif
     gArgs.AddArg("-prune=<n>", strprintf("Reduce storage requirements by enabling pruning (deleting) of old blocks. This allows the pruneblockchain RPC to be called to delete specific blocks, and enables automatic pruning of old blocks if a target size in MiB is provided. This mode is incompatible with -txindex and -rescan. "
             "Warning: Reverting this setting requires re-downloading the entire blockchain. "
-            "(default: 0 = disable pruning blocks, 1 = allow manual pruning via RPC, >%u = automatically prune block files to stay under the specified target size in MiB)", MIN_DISK_SPACE_FOR_BLOCK_FILES / 1024 / 1024), false, OptionsCategory::OPTIONS);
+            "(default: 0 = disable pruning blocks, 1 = allow manual pruning via RPC, >=%u = automatically prune block files to stay under the specified target size in MiB)", MIN_DISK_SPACE_FOR_BLOCK_FILES / 1024 / 1024), false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-reindex", "Rebuild chain state and block index from the blk*.dat files on disk", false, OptionsCategory::OPTIONS);
     gArgs.AddArg("-reindex-chainstate", "Rebuild chain state from the currently indexed blocks", false, OptionsCategory::OPTIONS);
 #ifndef WIN32