Doc update fermi (#762)

Author: zzzckck

docs/announce/fermi-bsc.md

@@ -18,5 +18,8 @@ There are five BEPs in Fermi:
 - [BEP-593: Incremental Snapshot](https://github.com/bnb-chain/BEPs/blob/master/BEPs/BEP-593.md)
 - [BEP-610: Implement EVM Super Instruction](https://github.com/bnb-chain/BEPs/blob/master/BEPs/BEP-610.md)
 
-## Upgrade BSC Testnet Nodes to v1.6.2 Before Hardfork
+## Upgrade BSC Testnet Nodes to v1.6.2+ Before Hardfork
 [v1.6.2](https://github.com/bnb-chain/bsc/releases/tag/v1.6.2) is a hard fork release for BSC Testnet, the HF name is: [Fermi](https://forum.bnbchain.org/t/bnb-chain-upgrades-testnet/934#p-1416-h-4-fermi-wip-5)
+
+## Upgrade BSC Mainnet Nodes to v1.6.4+ Before Hardfork
+[v1.6.4](https://github.com/bnb-chain/bsc/releases/tag/v1.6.4) is a hard fork release for BSC Testnet, the HF name is: [Fermi](https://forum.bnbchain.org/t/bnb-chain-roadmap-mainnet/936#p-1418-h-1-fermi-passed-8)

docs/announce/na.md

@@ -0,0 +1 @@
+# No Upcoming Upgrade Plan Yet

mkdocs.yml

@@ -62,9 +62,7 @@ nav:
   - Announcements:
     - Announcements: ./announce/index.md
     - Upcoming:
-      - Fermi Hardfork(BSC): ./announce/fermi-bsc.md
-      - Fourier Upgrade of opBNB: ./announce/fourier-opbnb.md
-
+      - NA: ./announce/na.md
     - Passed:
       - Fjord Hardfork(opBNB): ./announce/fjord-opbnb.md
       - Wright Hardfork(opBNB): ./announce/wright-opbnb.md
@@ -85,6 +83,8 @@ nav:
       - Lorentz Hardfork(BSC): ./announce/lorentz-bsc.md
       - Maxwell Hardfork(BSC): ./announce/maxwell-bsc.md
       - Volta Upgrade of opBNB: ./announce/volta-opbnb.md
+      - Fermi Hardfork(BSC): ./announce/fermi-bsc.md
+      - Fourier Upgrade of opBNB: ./announce/fourier-opbnb.md
 
   - BNB Smart Chain:
     - BNB Smart Chain: ./bnb-smart-chain/index.md