[PATCH evolve-ext] readme: mention patchbomb usage and patch description guidelines on wiki

[Faheem Mitha]

# HG changeset patch
# User Faheem Mitha <faheem at faheem.info>
# Date 1405268643 -19800
#      Sun Jul 13 21:54:03 2014 +0530
# Node ID 713303e81a3735f919c3b3cc64f04d214b72502e
# Parent  85ec2a55fe7ccaa4b0e24cf9872c07916cc793e3
readme: mention patchbomb usage and patch description guidelines on wiki

diff -r 85ec2a55fe7c -r 713303e81a37 README
--- a/README
+++ b/README
@@ -29,9 +29,19 @@
 ==========
 
 The simplest way to contribute is to issue a pull request on Bitbucket
-(https://bitbucket.org/marmoute/mutable-history). Please don't forget
-to update and run the tests when you fix a bug or add a feature. To
-run the tests:
+(https://bitbucket.org/marmoute/mutable-history). Alternatively, you
+can use the patchbomb extension to send email to mercurial
+devel. Please make sure to use the evolve-ext flag when doing so. You
+can use a command like this:
+
+    hg email --to mercurial-devel at selenic.com --flag evolve-ext --rev '<your patches>'
+
+See also
+http://mercurial.selenic.com/wiki/ContributingChanges#Patch_descriptions
+for guidelines on the patch description.
+
+Please don't forget to update and run the tests when you fix a bug or
+add a feature. To run the tests:
 
     cd tests
     python run-tests.py --with-hg=/path/to/hg
@@ -223,7 +233,7 @@
 
 0.3.0 -- 2012-06-27
 
-- 
+-
 - obsolete:  Add "latecomer" error detection (stabilize does not handle resolution yet)
 - evolve:    Introduce a new `uncommit` command to remove change from a changeset
 - rebase:    allow the use of --keep again
@@ -243,5 +253,3 @@
 - rebase:    handle --collapse
 - evolve:   add `obsolete` alias to `kill`
 - evolve:   add `evolve` alias to `stabilize`
-
-