;doc: update CLI usage texts

hledger/Hledger/Cli/Commands/Balancesheet.txt

@@ -6,10 +6,10 @@ sign, as in conventional financial statements.
 
 _FLAGS
 
-The asset and liability accounts shown are those accounts declared with
-the Asset or Cash or Liability type, or otherwise all accounts under a
-top-level asset or liability account (case insensitive, plurals
-allowed).
+This report shows accounts declared with the Asset, Cash or Liability
+type (see account types). Or if no such accounts are declared, it shows
+top-level accounts named asset or liability (case insensitive, plurals
+allowed) and their subaccounts.
 
 Example:
 

hledger/Hledger/Cli/Commands/Balancesheetequity.txt

@@ -5,10 +5,10 @@ normal positive sign, as in conventional financial statements.
 
 _FLAGS
 
-The asset, liability and equity accounts shown are those accounts
-declared with the Asset, Cash, Liability or Equity type, or otherwise
-all accounts under a top-level asset, liability or equity account (case
-insensitive, plurals allowed).
+This report shows accounts declared with the Asset, Cash, Liability or
+Equity type (see account types). Or if no such accounts are declared, it
+shows top-level accounts named asset, liability or equity (case
+insensitive, plurals allowed) and their subaccounts.
 
 Example:
 

hledger/Hledger/Cli/Commands/Cashflow.txt

@@ -6,15 +6,13 @@ financial statements.
 
 _FLAGS
 
-"Cash" assets are those accounts which are (or whose parents are)
-declared as Cash by an account directive, like this:
+This report shows accounts declared with the Cash type (see account
+types). Or if no such accounts are declared, it shows accounts
 
-account some:liquid:asset    ; type:C
-
-Or if there are no such declarations, all accounts
-
--   under a top-level asset account (case insensitive, plural allowed)
--   with some variation of cash, bank, checking or saving in their name.
+-   under a top-level account named asset (case insensitive, plural
+    allowed)
+-   whose name contains some variation of cash, bank, checking or
+    saving.
 
 More precisely: all accounts matching this case insensitive regular
 expression:

hledger/Hledger/Cli/Commands/Incomestatement.txt

@@ -1,15 +1,14 @@
 incomestatement, is
-
 This command displays an income statement, showing revenues and expenses
 during one or more periods. Amounts are shown with normal positive sign,
 as in conventional financial statements.
 
 _FLAGS
 
-The revenue and expense accounts shown are those accounts declared with
-the Revenue or Expense type, or otherwise all accounts under a top-level
-revenue or income or expense account (case insensitive, plurals
-allowed).
+This report shows accounts declared with the Revenue or Expense type
+(see account types). Or if no such accounts are declared, it shows
+top-level accounts named revenue or income or expense (case insensitive,
+plurals allowed) and their subaccounts.
 
 Example: