mu4e: Don't use (mu4e-root-maildir) with easy-accounts

Use an older version, and update the docs.

mu4e/mu4e-context.el

@@ -109,11 +109,14 @@ none."
 Also:
 - Add the context to the `mu4e-contexts'.
 - Update the bookmarks to ignore the trash folder if NO-TRASH-FLAG is non-nil.
+- Update the `mu4e-user-mail-address-list'.
 
 Options beyond those of `make-mu4e-context':
 - `user-mail-address': Defaults to the global value when the context is created.
 - `smtpmail-smtp-user': Defaults to the global value if non-nil when the context
   is created, or the context `user-mail-address' otherwise.
+- `maildir': Mailbox folder name in as stored in `mu4e-maildir' (just the name,
+  there must be no '/').  Defaults to `name'.
 - `drafts-folder': Context value of `mu4e-drafts-folder'.  Defaults to
   \"drafts\".
 - `sent-folder': Context value of `mu4e-sent-folder'.  Defaults to \"sent\".
@@ -146,7 +149,7 @@ default folders (see `make-mu4e-context' and `mu4e-context'):
                    msg '(:from :to) \"boss@work.org\"))
      :vars gandi-smtp-vars))"
   (cl-assert name)
-  (setq maildir (concat "/" (mu4e-root-maildir) "/")
+  (setq maildir (concat "/" (or maildir name) "/")
         smtpmail-smtp-user (or smtpmail-smtp-user user-mail-address)
         no-trash-flag (or no-trash-flag
                           (string-match (regexp-opt mu4e-no-trash-providers)
@@ -189,6 +192,8 @@ default folders (see `make-mu4e-context' and `mu4e-context'):
                     (mu4e-trash-folder . ,mu4e-trash-folder)
                     (mu4e-refile-folder . ,mu4e-refile-folder))
                   (mu4e-context-vars context)))
+    ;; Required when using multiple addresses and if we don't want to
+    ;; reply to ourselves.
     (add-to-list 'mu4e-contexts context)
     context))
 

mu4e/mu4e.texi

@@ -2506,7 +2506,7 @@ example:
 * Context policies::How to determine the current context
 * Contexts and special folders::Using context variables to determine them
 * Contexts example::How to define contexts
-* Account setup helper::Easy context creation with sane defaults
+* Account setup helper::Context creation with reasonable defaults
 @end menu
 
 It can be useful to switch between different sets of settings in
@@ -2720,11 +2720,11 @@ and commas and note the '.' between variable name and its value.
 @node Account setup helper
 @section Account setup helper
 
-Contexts can be cumbersome to set up.  Thankfully @code{mu4e} provides a
-helper function @code{make-mu4e-context-account} to easily get started.
-The function helps initializing the context plus a couple of variables
-with sane defaults.
-Everything should work out of the box in most cases.
+Contexts can be cumbersome to set up. Thankfully @code{mu4e} provides
+a helper function @code{make-mu4e-context-account} to easily get
+started. The function helps initializing the context plus a couple of
+variables with reasonable defaults. Everything should work out of the
+box in most cases.
 
 A short example for two contexts:
 
@@ -2757,6 +2757,9 @@ They will be automatically stored under the maildir.
 @item When the @code{match-func} is not provided, the context is matched
 against @code{predicate} if provided or the maildir of the current
 message otherwise.
+@item If the e-mail address for some account is not already known to @t{mu}, you
+should probably @t{mu} about it with the @t{--my-address} parameter to
+@t{mu init}.
 @end itemize
 
 If the context created by @code{make-mu4e-context-account} is not