Remove outdated comments from requirements files

Recent pip no longer requires specific order and can resolve
dependencies automatically.

Also add note to set the right expectation about requirements lower
bounds.

Change-Id: I5a055974c446a7399da93794469cee1120ec63c2
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>
diff --git a/doc/requirements.txt b/doc/requirements.txt
index 2a94e8b..764591e 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,7 +1,3 @@
-# The order of packages is significant, because pip processes them in the order
-# of appearance. Changing the order has an impact on the overall integration
-# process, which may cause wedges in the gate later.
-
 sphinxcontrib-apidoc>=0.2.0 # BSD
 sphinx>=2.0.0,!=2.1.0 # BSD
 openstackdocstheme>=2.2.1 # Apache-2.0
diff --git a/requirements.txt b/requirements.txt
index afa0565..903b11b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,6 @@
-# The order of packages is significant, because pip processes them in the order
-# of appearance. Changing the order has an impact on the overall integration
-# process, which may cause wedges in the gate later.
+# Requirements lower bounds listed here are our best effort to keep them up to
+# date but we do not test them so no guarantee of having them all correct. If
+# you find any incorrect lower bounds, let us know or propose a fix.
 
 cryptography>=3.0 # BSD/Apache-2.0
 python-dateutil>=2.5.3 # BSD
diff --git a/test-requirements.txt b/test-requirements.txt
index bb4fcfe..c63a971 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,7 +1,3 @@
-# The order of packages is significant, because pip processes them in the order
-# of appearance. Changing the order has an impact on the overall integration
-# process, which may cause wedges in the gate later.
-
 hacking>=6.1.0,<6.2.0 # Apache-2.0
 
 coverage!=4.4,>=4.0 # Apache-2.0