;doc: update CLI usage texts

hledger/Hledger/Cli/Commands/Add.txt

@@ -7,10 +7,10 @@ _FLAGS
 Many hledger users edit their journals directly with a text editor, or
 generate them from CSV. For more interactive data entry, there is the
 add command, which prompts interactively on the console for new
-transactions, and appends them to the journal file (if there are
+transactions, and appends them to the main journal file (which should be
-multiple -f FILE options, the first file is used.) Existing transactions
+in journal format). Existing transactions are not changed. This is one
-are not changed. This is the only hledger command that writes to the
+of the few hledger commands that writes to the journal file (see also
-journal file.
+import).
 
 To use it, just run hledger add and follow the prompts. You can add as
 many transactions as you like; when you are finished, enter . or press

hledger/Hledger/Cli/Commands/Cashflow.txt

@@ -1,16 +1,29 @@
 cashflow, cf
 This command displays a cashflow statement, showing the inflows and
-outflows affecting "cash" (ie, liquid) assets. Amounts are shown with
+outflows affecting "cash" (ie, liquid, easily convertible) assets.
-normal positive sign, as in conventional financial statements.
+Amounts are shown with normal positive sign, as in conventional
+financial statements.
 
 _FLAGS
 
-The "cash" accounts shown are those accounts declared with the Cash
+"Cash" assets are those accounts which are (or whose parents are)
-type, or otherwise all accounts under a top-level asset account (case
+declared as Cash by an account directive, like this:
-insensitive, plural allowed) which do not have fixed, investment,
-receivable or A/R in their name.
 
-Example:
+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.
+
+More precisely: all accounts matching this case insensitive regular
+expression:
+
+^assets?(:.+)?:(cash|bank|che(ck|que?)(ing)?|savings?|currentcash)(:|$)
+
+and their subaccounts.
+
+An example cashflow report:
 
 $ hledger cashflow
 Cashflow Statement

hledger/Hledger/Cli/Commands/Import.txt

@@ -1,11 +1,16 @@
 import
 Read new transactions added to each FILE since last run, and add them to
-the main journal file. Or with --dry-run, just print the transactions
+the journal. Or with --dry-run, just print the transactions that would
-that would be added. Or with --catchup, just mark all of the FILEs'
+be added. Or with --catchup, just mark all of the FILEs' transactions as
-transactions as imported, without actually importing any.
+imported, without actually importing any.
 
 _FLAGS
 
+This command may append new transactions to the main journal file (which
+should be in journal format). Existing transactions are not changed.
+This is one of the few hledger commands that writes to the journal file
+(see also add).
+
 Unlike other hledger commands, with import the journal file is an output
 file, and will be modified, though only by appending (existing data will
 not be changed). The input files are specified as arguments, so to