docs: fixing other mining references

src/pages/404.md

@@ -25,7 +25,7 @@ Looks like the page you are looking for isn't here. Try out some of these popula
 ## Start mining
 
 [@page-reference | grid]
-| /start-mining, /understand-stacks/running-testnet-node
+| /start-mining/mainnet, /start-mining/testnet, /understand-stacks/running-testnet-node, /understand-stacks/running-mainnet-node
 
 ## Ecosystem
 

src/pages/index.md

@@ -21,7 +21,7 @@ description: Write Clarity smart contracts, build apps, and starting mining with
 ## Start mining
 
 [@page-reference | grid]
-| /start-mining/mainnet, /start-mining/testnet, /understand-stacks/running-testnet-node
+| /start-mining/mainnet, /start-mining/testnet, /understand-stacks/running-testnet-node, /understand-stacks/running-mainnet-node
 
 ## Ecosystem
 

src/pages/understand-stacks/stacking.md

@@ -70,7 +70,7 @@ Miners have to run a software (mining client, aka "miner") on their machines to
 - Assembly: The elected miner writes the new block and collects rewards in form of new Stacks (STX) tokens
 
 [@page-reference | inline]
-| /start-mining
+| /start-mining/mainnet, /start-mining/testnet
 
 ## Token holder eligibility