Updated important missing enviroment variables (#344)

[ROCm/rocshmem commit: 8b350a51fe]

projects/rocshmem/docs/api/env_variables.rst

@@ -2,6 +2,8 @@
   :description: rocSHMEM environment variables reference
   :keywords: rocSHMEM, ROCm, API, environment variables, environment, reference
 
+.. _rocshmem-api-env-variables:
+
 ********************************************************************
 rocSHMEM environment variables
 ********************************************************************
@@ -33,6 +35,14 @@ control the behavior of rocSHMEM.
       - ``40``
       - Maximum number of teams.
 
+    * - | ``ROCSHMEM_BACKEND``
+        | When rocSHMEM is compiled for all backends, this enviroment variable
+        | selects which backend to execute. Default is auto-selection
+      - ````
+      - | ipc: IPC Backend
+        | ro: Reverse Offload Backend
+        | gda: GPU Direct Async Backend
+
     * - | ``ROCSHMEM_UNIQUEID_WITH_MPI``
         | Defines whether rocSHMEM is expected to use MPI when using the uniqueId based initialization.
       - ``0``
@@ -45,14 +55,42 @@ control the behavior of rocSHMEM.
       - | 0: Use IPC when available.
         | 1: Force network conduit.
 
+    * - | ``ROCSHMEM_USE_IB_HCA``
+        | Defines which NIC that this PE should be bound to
+      - ``0``
+      - | Example value: `bnxt_re0`
+
+    * - | ``ROCSHMEM_BOOTSTRAP_SOCKET_IFNAME``
+        | Chooses the interface to bootstrap rocSHMEM with.
+        | Only valid when not using MPI.
+        | The default value is an empty string and rocSHMEM auto-detects the most appropriate interface.
+      - ````
+      - | Example value: `eno8303`
+
+    * - | ``ROCSHMEM_GDA_PROVIDER``
+        | When rocSHMEM is compiled with support for multiple NIC vendors,
+        | the enviroment variable selects the desired provider.
+        | The default value is an empty string and rocSHMEM auto-detects the most appropriate NIC.
+      - ````
+        | bnxt: Broadcom Thor 2
+        | pensando: AMD Pensando Pollara
+        | ionic: AMD Pensando Pollara (alias)
+        | mlx5: Mellanox ConnectX-7
+
     * - | ``ROCSHMEM_GDA_ALTERNATE_QP_PORTS``
         | Enables/Disables having QPs alternate their mappings across rocSHMEM contexts.
       - ``1``
       - | 0: Disabled.
         | 1: Enabled (helps saturate bandwidth on multiport bonded interfaces).
 
+    * - | ``ROCSHMEM_GDA_TRAFFIC_CLASS``
+        | When using an NIC with an Ethernet link layer, this assigns the traffic class for our QPs
+      - ``0``
+      - The traffic class number.
+
     * - | ``ROCSHMEM_GDA_PCIE_RELAXED_ORDERING``
         | Enables PCIe Relaxed Ordering when registering the symmetric heap with the RDMA NICs.
       - ``0``
       - | 0: Disabled.
         | 1: Enabled.
+