DOC-5934 RS: Calculate percent memory usage for v2 metrics (#2363)

Author: rrelledge

content/embeds/rs-prometheus-metrics-transition-plan.md

@@ -230,7 +230,7 @@
 | <span class="break-all">redis_master_repl_offset</span> | <span class="break-all">`redis_server_master_repl_offset`</span> | Number of bytes sent to replicas by the shard; calculate the throughput for a time period by comparing the value at different times |
 | <span class="break-all">redis_master_sync_in_progress</span> | <span class="break-all">`redis_server_master_sync_in_progress`</span> | The master shard is synchronizing (1 true; 0 false) |
 | <span class="break-all">redis_max_process_mem</span> | <span class="break-all">`redis_server_max_process_mem`</span> | Current memory limit configured by redis_mgr according to node free memory |
-| <span class="break-all">redis_maxmemory</span> | <span class="break-all">`redis_server_maxmemory`</span> | Current memory limit configured by redis_mgr according to database memory limits |
+| <span class="break-all">redis_maxmemory</span> | <span class="break-all">`redis_server_maxmemory`</span> | Current memory limit configured by redis_mgr according to database memory limits. <br /><br />To calculate the percent memory usage:<br /><span class="break-all">`sum by (cluster,db)(redis_server_used_memory{role="master"}) / (avg by(cluster,db)(db_memory_limit_bytes) / max by(cluster,db)(db_replication_factor))`</span> |
 | <span class="break-all">redis_mem_aof_buffer</span> | <span class="break-all">`redis_server_mem_aof_buffer`</span> | Current size of AOF buffer |
 | <span class="break-all">redis_mem_clients_normal</span> | <span class="break-all">`redis_server_mem_clients_normal`</span> | Current memory used for input and output buffers of non-replica clients |
 | <span class="break-all">redis_mem_clients_slaves</span> | <span class="break-all">`redis_server_mem_clients_slaves`</span> | Current memory used for input and output buffers of replica clients |

content/embeds/rs-prometheus-metrics-v2.md

@@ -144,7 +144,7 @@
 | redis_server_master_repl_offset | Number of bytes sent to replicas by the shard; calculate the throughput for a time period by comparing the value at different times |
 | <span class="break-all">redis_server_master_sync_in_progress</span> | The primary shard is synchronizing (1 true; 0 false) |
 | redis_server_max_process_mem | Current memory limit configured by redis_mgr according to node free memory |
-| redis_server_maxmemory | Current memory limit configured by redis_mgr according to database memory limits |
+| redis_server_maxmemory | Current memory limit configured by redis_mgr according to database memory limits. <br /><br />To calculate the percent memory usage:<br /><span class="break-all">`sum by (cluster,db)(redis_server_used_memory{role="master"}) / (avg by(cluster,db)(db_memory_limit_bytes) / max by(cluster,db)(db_replication_factor))`</span> |
 | redis_server_mem_aof_buffer | Current size of AOF buffer |
 | redis_server_mem_clients_normal | Current memory used for input and output buffers of non-replica clients |
 | redis_server_mem_clients_slaves | Current memory used for input and output buffers of replica clients |