Fix typo in SSD_index.md (#466)

workflows/SSD_index.md

@@ -11,7 +11,7 @@ The arguments are as follows:
 3. **--data_file**: The input data over which to build an index, in .bin format. The first 4 bytes represent number of points as an integer. The next 4 bytes represent the dimension of data as an integer. The following `n*d*sizeof(T)` bytes contain the contents of the data one data point in time. `sizeof(T)` is 1 for byte indices, and 4 for float indices. This will be read by the program as int8_t for signed indices, uint8_t for unsigned indices or float for float indices.
 4. **--index_path_prefix**: the index will span a few files, all beginning with the specified prefix path. For example, if you provide `~/index_test` as the prefix path, build  generates files such as `~/index_test_pq_pivots.bin, ~/index_test_pq_compressed.bin, ~/index_test_disk.index, ...`. There may be between 8 and 10 files generated with this prefix depending on how the index is constructed.
 5. **-R (--max_degree)**  (default is 64): the degree of the graph index, typically between 60 and 150. Larger R will result in larger indices and longer indexing times, but better search quality. 
-6. **-L (--Lbuild)**  (default is 100): the size of search listduring index build. Typical values are between 75 to 200. Larger values will take more time to build but result in indices that provide higher recall for the same search complexity. Use a value for L value that is at least the value of R unless you need to build indices really quickly and can somewhat compromise on quality. 
+6. **-L (--Lbuild)**  (default is 100): the size of search list during index build. Typical values are between 75 to 200. Larger values will take more time to build but result in indices that provide higher recall for the same search complexity. Use a value for L value that is at least the value of R unless you need to build indices really quickly and can somewhat compromise on quality. 
 7. **-B (--search_DRAM_budget)**: bound on the memory footprint of the index at search time in GB. Once built, the index will use up only the specified RAM limit, the rest will reside on disk. This will dictate how aggressively we compress the data vectors to store in memory. Larger will yield better performance at search time. For an n point index, to use b byte PQ compressed representation in memory, use `B = ((n * b) / 2^30  + (250000*(4*R + sizeof(T)*ndim)) / 2^30)`. The second term in the summation is to allow some buffer for caching about 250,000 nodes from the graph in memory while serving.  If you are not sure about this term, add 0.25GB to the first term. 
 8. **-M (--build_DRAM_budget)**: Limit on the memory allowed for building the index in GB. If you specify a value less than what is required to build the index in one pass, the index is  built using a divide and conquer approach so that  sub-graphs will fit in the RAM budget. The sub-graphs are overlayed to build the overall index. This approach can be upto 1.5 times slower than building the index in one shot. Allocate as much memory as your RAM allows.
 9. **-T (--num_threads)** (default is to get_omp_num_procs()): number of threads used by the index build process. Since the code is highly parallel, the  indexing time improves almost linearly with the number of threads (subject to the cores available on the machine and DRAM bandwidth).
@@ -34,7 +34,7 @@ The arguments are as follows:
 8. **--gt_file**: The ground truth file for the queries in arg (7) and data file used in index construction.  The binary file must start with *n*, the number of queries (4 bytes), followed by *d*, the number of ground truth elements per query (4 bytes), followed by `n*d` entries per query representing the d closest IDs per query in integer format,  followed by `n*d` entries representing the corresponding distances (float). Total file size is `8 + 4*n*d + 4*n*d` bytes. The groundtruth file, if not available, can be calculated using the program `apps/utils/compute_groundtruth`. Use "null" if you do not have this file and if you do not want to compute recall.
 9. **K**: search for *K* neighbors and measure *K*-recall@*K*, meaning the intersection between the retrieved top-*K* nearest neighbors and ground truth *K* nearest neighbors.
 10. **result_output_prefix**: Search results will be stored in files with specified prefix, in bin format.
-11. **-L (--search_list)**: A list of search_list sizes to perform search with. Larger parameters will result in slower latencies, but higher accuracies. Must be atleast the value of *K* in arg (9).
+11. **-L (--search_list)**: A list of search_list sizes to perform search with. Larger parameters will result in slower latencies, but higher accuracies. Must be at least the value of *K* in arg (9).
 
 
 Example with BIGANN:
@@ -60,7 +60,7 @@ Now build and search the index and measure the recall using ground truth compute
  ./apps/search_disk_index  --data_type float --dist_fn l2 --index_path_prefix data/sift/disk_index_sift_learn_R32_L50_A1.2 --query_file data/sift/sift_query.fbin  --gt_file data/sift/sift_query_learn_gt100 -K 10 -L 10 20 30 40 50 100 --result_path data/sift/res --num_nodes_to_cache 10000
  ```
 
-The search might be slower on machine with remote SSDs. The output lists the quer throughput, the mean and 99.9pc latency in microseconds and mean number of 4KB IOs to disk for each `L` parameter provided. 
+The search might be slower on machine with remote SSDs. The output lists the query throughput, the mean and 99.9pc latency in microseconds and mean number of 4KB IOs to disk for each `L` parameter provided. 
 
 ```
     L   Beamwidth             QPS    Mean Latency    99.9 Latency        Mean IOs         CPU (s)       Recall@10