Help cleanup

Large list of changes, including formatting and typos for most commands.

More substantive changes have been made to alias, bind, block, break,
builtin, case, cd, commandline, count, else, emit, fish_config, funced,
function, functions, history, math, mimedb, nextd, not, popd, prevd,
pushd, pwd, random, read, set, set_color, switch, test, trap, type,
ulimit, umask, and while.

doc_src/history.txt

@@ -1,4 +1,4 @@
-\section history history - Show and manipulate user's command history 
+\section history history - Show and manipulate command history
 
 \subsection history-synopsis Synopsis
 <pre>
@@ -8,29 +8,37 @@ history (--search | --delete ) (--prefix "prefix string" | --contains "search st
 
 \subsection history-description Description
 
-history is used to list, search and delete user's command history
+\c history is used to list, search and delete the history of commands used.
+
+The following options are available:
+
+- \c --save saves all changes in the history file. The shell automatically
+saves the history file; this option is provided for internal use.
+- \c --clear clears the history file. A prompt is displayed before the history
+is erased.
+- \c --search returns history items in keeping with the \c --prefix or
+\c --contains options.
+- \c --delete deletes history items.
+- \c --prefix searches or deletes items in the history that begin with the
+specified text string.
+- \c --contains searches or deletes items in the history that contain the
+specified text string.
+
+If \c --search is specified without \c --contains or <code>--prefix</code>,
+\c --contains will be assumed.
+
+If \c --delete is specified without \c --contains or <code>--prefix</code>,
+only a history item which exactly matches the parameter will be erased. No
+prompt will be given. If \c --delete is specified with either of these
+parameters, an interactive prompt will be displayed before any items are
+deleted.
 
 \subsection history-examples Example
 
-<pre>
-history --save
-Save all changes in history file
+<code>history --clear</code> deletes all history items
 
-history --clear
-Delete all history items
+<code>history --search --contains "foo"</code> outputs a list of all previous
+commands containing the string "foo".
 
-history --search --contains "foo"
-Searches commands containing "foo" string
-
-history --search --prefix "foo"
-Searches for commands with prefix "foo"
-
-history --delete --contains "foo"
-Interactively delete commands containing string "foo"
-
-history --delete --prefix "foo"
-Interactively delete commands with prefix "foo"
-
-history --delete "foo"
-Delete command "foo" from history
-</pre>
+<code>history --delete --prefix "foo"</code> interactively deletes the record
+of previous commands which start with "foo".