Update docs to reflect new if/while condtion chaining

Documents new behavior in #1428

Cherry picked from 30ea7cc3f8

doc_src/and.txt

@@ -7,11 +7,12 @@ COMMAND1; and COMMAND2
 
 \subsection and-description Description
 
-`and` is used to execute a command if the current exit status (as set by the last previous command) is 0.
+`and` is used to execute a command if the current exit status (as set by the previous command) is 0.
 
-`and` does not change the current exit status.
+`and` statements may be used as part of the condition in an <a href="#if">`and`</a> or <a href="#while">`while`</a> block. See the documentation
+for <a href="#if">`if`</a> and <a href="#while">`while`</a> for examples.
 
-The exit status of the last foreground command to exit can always be accessed using the <a href="index.html#variables-status">$status</a> variable.
+`and` does not change the current exit status. The exit status of the last foreground command to exit can always be accessed using the <a href="index.html#variables-status">$status</a> variable.
 
 
 \subsection and-example Example

doc_src/if.txt

@@ -12,7 +12,7 @@ end
 
 `if` will execute the command `CONDITION`. If the condition's exit status is 0, the commands `COMMANDS_TRUE` will execute.  If the exit status is not 0 and `else` is given, `COMMANDS_FALSE` will be executed.
 
-In order to use the exit status of multiple commands as the condition of an if block, use <a href="#begin">`begin; ...; end`</a> and the short circuit commands <a href="commands.html#and">`and`</a> and <a href="commands.html#or">`or`</a>.
+You can use <a href="#and">`and`</a> or <a href="#and">`or`</a> in the condition. See the second example below.
 
 The exit status of the last foreground command to exit can always be accessed using the <a href="index.html#variables-status">$status</a> variable.
 
@@ -33,9 +33,8 @@ end
 
 The following code will print "foo.txt exists and is readable" if foo.txt is a regular file and readable
 \fish
-if begin test -f foo.txt
+if test -f foo.txt
    and test -r foo.txt
-		 end
    echo "foo.txt exists and is readable"
 end
 \endfish

doc_src/or.txt

@@ -7,12 +7,12 @@ COMMAND1; or COMMAND2
 
 \subsection or-description Description
 
-`or` is used to execute a command if the current exit status (as set by the last previous command) is not 0.
+`or` is used to execute a command if the current exit status (as set by the previous command) is not 0.
 
-`or` does not change the current exit status.
-
-The exit status of the last foreground command to exit can always be accessed using the <a href="index.html#variables-status">$status</a> variable.
+`or` statements may be used as part of the condition in an <a href="#if">`and`</a> or <a href="#while">`while`</a> block. See the documentation
+for <a href="#if">`if`</a> and <a href="#while">`while`</a> for examples.
 
+`or` does not change the current exit status. The exit status of the last foreground command to exit can always be accessed using the <a href="index.html#variables-status">$status</a> variable.
 
 \subsection or-example Example
 

doc_src/while.txt

@@ -11,12 +11,11 @@ while CONDITION; COMMANDS...; end
 
 If the exit status of `CONDITION` is non-zero on the first iteration, `COMMANDS` will not be executed at all.
 
-Use <a href="#begin">`begin; ...; end`</a> for complex conditions; more complex control can be achieved with `while true` containing a <a href="#break">break</a>.
-
+You can use <a href="#and">`and`</a> or <a href="#and">`or`</a> for complex conditions. Even more complex control can be achieved with `while true` containing a <a href="#break">break</a>.
 
 \subsection while-example Example
 
 \fish
-while test -f foo.txt; echo file exists; sleep 10; end
-# outputs 'file exists' at 10 second intervals as long as the file foo.txt exists.
+while test -f foo.txt; or test -f bar.txt ; echo file exists; sleep 10; end
+# outputs 'file exists' at 10 second intervals as long as the file foo.txt or bar.txt exists.
 \endfish