CommitMessage: synchronize line length recommendation This brings it in line with gerrit and /doc/contribute, updated in CL 727860. Change-Id: Icf75750baa92d0564253af8511a745c06a6a6964 Reviewed-on: https://go-review.googlesource.com/c/wiki/+/729840 Reviewed-by: Sean Liao <sean@liao.dev>

diff --git a/CommitMessage.md b/CommitMessage.md
index e7c8532..b0b4951 100644
--- a/CommitMessage.md
+++ b/CommitMessage.md

@@ -18,11 +18,11 @@
 - the part after the colon uses the verb tense + phrase that completes the blank in, _"this change modifies Go to \***\*\_\_\_\*\***"_
 - the verb after the colon is lowercase
 - there is no trailing period
-- it should be kept as short as possible (many git viewing tools prefer under ~76 characters, though Go isn't super strict about this).
+- it should be kept as short as possible (many git viewing tools prefer under ~72 characters, though Go isn't super strict about this).
 
 For the body (the rest of the description):
 
-- the text should be wrapped to ~76 characters (to appease git viewing tools, mainly), unless you really need longer lines (e.g. for ASCII art, tables, or long links).
+- the text should be wrapped to ~72 characters (to appease git viewing tools, mainly), unless you really need longer lines (e.g. for ASCII art, tables, or long links).
 - the Fixes line goes after the body with a blank newline separating the two. (It is acceptable but not required to use a trailing period, such as `Fixes #12345.`).
 - there is **no** Markdown in the commit message.
 - we **do not** use `Signed-off-by` lines. Don't add them. Our Gerrit server & GitHub bots enforce CLA compliance instead.