;doc: update command docs

Author: simonmichael

hledger/Hledger/Cli/Commands/Rewrite.txt

@@ -125,7 +125,7 @@ from hledger print.
 
 See also:
 
-https://github.com/simonmichael/hledger/issues/99
+https://github.com/plaintextaccounting/hledger/issues/99
 
 rewrite vs. print --auto
 

hledger/Hledger/Cli/Commands/Roi.txt

@@ -43,7 +43,7 @@ Note, in some cases this report can fail, for these reasons:
 Examples:
 
 - Using roi to compute total return of investment in stocks:
-  https://github.com/simonmichael/hledger/blob/main/examples/investing/roi-unrealised.ledger
+  https://github.com/plaintextaccounting/hledger/blob/main/examples/investing/roi-unrealised.ledger
 
 - Cookbook > Return on Investment: https://hledger.org/roi.html