module documentation mismatches: loading and fork child for 5.0 branch

loading flag was missing from docs, and fork chidl indicator was removed from
the code but left int he doc and header, re-adding it to the doc together with
the missing function that was needed for it to work.

src/module.c

@@ -1518,6 +1518,8 @@ int RM_GetSelectedDb(RedisModuleCtx *ctx) {
  *  * REDISMODULE_CTX_FLAGS_OOM_WARNING: Less than 25% of memory remains before
  *                                       reaching the maxmemory level.
  *
+ *  * REDISMODULE_CTX_FLAGS_LOADING: Server is loading RDB/AOF
+ *
  *  * REDISMODULE_CTX_FLAGS_REPLICA_IS_STALE: No active link with the master.
  *
  *  * REDISMODULE_CTX_FLAGS_REPLICA_IS_CONNECTING: The replica is trying to
@@ -1596,6 +1598,9 @@ int RM_GetContextFlags(RedisModuleCtx *ctx) {
     if (retval == C_ERR) flags |= REDISMODULE_CTX_FLAGS_OOM;
     if (level > 0.75) flags |= REDISMODULE_CTX_FLAGS_OOM_WARNING;
 
+    /* Presence of children processes. */
+    if (hasActiveChildProcess()) flags |= REDISMODULE_CTX_FLAGS_ACTIVE_CHILD;
+
     return flags;
 }
 

src/server.c

@@ -779,6 +779,11 @@ void updateDictResizePolicy(void) {
         dictDisableResize();
 }
 
+int hasActiveChildProcess() {
+    return server.rdb_child_pid != -1 ||
+           server.aof_child_pid != -1;
+}
+
 /* ======================= Cron: called every 100 ms ======================== */
 
 /* Add a sample to the operations per second array of samples. */

src/server.h

@@ -1653,6 +1653,7 @@ void openChildInfoPipe(void);
 void closeChildInfoPipe(void);
 void sendChildInfo(int process_type);
 void receiveChildInfo(void);
+int hasActiveChildProcess();
 
 /* Sorted sets data type */