Misc doc fixes (facebook#8983)

Summary:
- Update few stale GitHub wiki link references from rocksdb.org
- Update the API comments for ignore_range_deletions

Pull Request resolved: facebook#8983

Reviewed By: ajkr

Differential Revision: D31355965

Pulled By: ramvadiv

fbshipit-source-id: 245ac4a6913976dd82afa308bc4aae6bff3d788c

db/compaction/compaction_picker_universal.cc

@@ -104,7 +104,7 @@ class UniversalCompactionBuilder {
   // because some files are being compacted.
   Compaction* PickPeriodicCompaction();
 
-  // Used in universal compaction when the enabled_trivial_move
+  // Used in universal compaction when the allow_trivial_move
   // option is set. Checks whether there are any overlapping files
   // in the input. Returns true if the input files are non
   // overlapping.

docs/_docs/getting-started.md

@@ -73,6 +73,6 @@ These are just simple examples of how RocksDB is used. The full documentation is
 
 Here are some specific details about the RocksDB implementation:
 
-- [Architecture Guide](https://github.com/facebook/rocksdb/wiki/Rocksdb-Architecture-Guide)
-- [Format of an immutable Table file](https://github.com/facebook/rocksdb/wiki/Rocksdb-Table-Format)
-- [Format of a log file](https://github.com/facebook/rocksdb/wiki/Write-Ahead-Log-File-Format)
+- [RocksDB Overview](https://github.com/facebook/rocksdb/wiki/RocksDB-Overview)
+- [Immutable BlockBased Table file format](https://github.com/facebook/rocksdb/wiki/Rocksdb-BlockBasedTable-Format)
+- [Log file format](https://github.com/facebook/rocksdb/wiki/Write-Ahead-Log-File-Format)

docs/_top-level/support.md

@@ -19,4 +19,4 @@ Use the [RocksDB Facebook group](https://www.facebook.com/groups/rocksdb.dev/) f
 
 ### FAQ
 
-Check out a list of [commonly asked questions](/docs/support/faq) about RocksDB.
+Check out a list of [commonly asked questions](https://github.com/facebook/rocksdb/wiki/RocksDB-FAQ) about RocksDB.

include/rocksdb/options.h

@@ -1516,9 +1516,11 @@ struct ReadOptions {
   // Default: false
   bool background_purge_on_iterator_cleanup;
 
-  // If true, keys deleted using the DeleteRange() API will be visible to
-  // readers until they are naturally deleted during compaction. This improves
-  // read performance in DBs with many range deletions.
+  // If true, range tombstones handling will be skipped in key lookup paths.
+  // For DB instances that don't use DeleteRange() calls, this setting can
+  // be used to optimize the read performance.
+  // Note that, if this assumption (of no previous DeleteRange() calls) is
+  // broken, stale keys could be served in read paths.
   // Default: false
   bool ignore_range_deletions;