Use upper case for Q unit

"The unit 'Q' is very common in Japanese typesetting"
https://lists.w3.org/Archives/Public/www-style/2013Nov/0302.html
http://tosche.net/2013/10/font-size-in-the-metric-system_e.html

css-values-3/Overview.bs

@@ -1048,13 +1048,13 @@ Viewport-percentage lengths: the ''vw'', ''vh'', ''vmin'', ''vmax'' units</h4>
 -->
 
 <h3 id="absolute-lengths">
-Absolute lengths: the ''cm'', ''mm'', ''q'', ''in'', ''pt'', ''pc'', ''px'' units</h3>
+Absolute lengths: the ''cm'', ''mm'', ''Q'', ''in'', ''pt'', ''pc'', ''px'' units</h3>
 
 	The <dfn lt="absolute length">absolute length units</dfn> are fixed in relation to each other
 	and anchored to some physical measurement.
 	They are mainly useful when the output environment is known.
 	The absolute units consist of
-	the <dfn>physical units</dfn> (''in'', ''cm'', ''mm'', ''pt'', ''pc'', ''q'')
+	the <dfn>physical units</dfn> (''in'', ''cm'', ''mm'', ''pt'', ''pc'', ''Q'')
 	and the <dfn>visual angle unit</dfn> (''px''):
 
 	<table class="data" export>
@@ -1069,9 +1069,9 @@ Absolute lengths: the ''cm'', ''mm'', ''q'', ''in'', ''pt'', ''pc'', ''px'' unit
 		<tr><th><dfn id="mm">mm</dfn>
 		    <td>millimeters
 		    <td>1mm = 1/10th of 1cm
-		<tr><th><dfn id="q">q</dfn>
+		<tr><th><dfn id="Q">Q</dfn>
 		    <td>quarter-millimeters
-		    <td>1q = 1/40th of 1cm
+		    <td>1Q = 1/40th of 1cm
 		<tr><th><dfn id="in">in</dfn>
 		    <td>inches
 		    <td>1in = 2.54cm = 96px
@@ -2174,7 +2174,7 @@ Changes</h2>
 
 	<ul>
 		<li>Specified that, in the absence of font information, ''1ch'' equal ''.5em''.
-		<li>Added ''q'' unit.
+		<li>Added ''Q'' unit.
 		<li>Relaxed unnecessary restrictions on <<custom-ident>>.
 			Require specs referencing it to be clear about excluded keywords,
 			because the new rule isn't as simple.

css-values/Overview.bs

@@ -1145,13 +1145,13 @@ Viewport-percentage lengths: the ''vw'', ''vh'', ''vi'', ''vb'', ''vmin'', ''vma
 -->
 
 <h3 id="absolute-lengths">
-Absolute lengths: the ''cm'', ''mm'', ''q'', ''in'', ''pt'', ''pc'', ''px'' units</h3>
+Absolute lengths: the ''cm'', ''mm'', ''Q'', ''in'', ''pt'', ''pc'', ''px'' units</h3>
 
 	The <dfn lt="absolute length">absolute length units</dfn> are fixed in relation to each other
 	and anchored to some physical measurement.
 	They are mainly useful when the output environment is known.
 	The absolute units consist of
-	the <dfn>physical units</dfn> (''in'', ''cm'', ''mm'', ''pt'', ''pc'', ''q'')
+	the <dfn>physical units</dfn> (''in'', ''cm'', ''mm'', ''pt'', ''pc'', ''Q'')
 	and the <dfn>visual angle unit</dfn> (''px''):
 
 	<table class="data" export>
@@ -1166,9 +1166,9 @@ Absolute lengths: the ''cm'', ''mm'', ''q'', ''in'', ''pt'', ''pc'', ''px'' unit
 		<tr><th><dfn id="mm">mm</dfn>
 		    <td>millimeters
 		    <td>1mm = 1/10th of 1cm
-		<tr><th><dfn id="q">q</dfn>
+		<tr><th><dfn id="Q">Q</dfn>
 		    <td>quarter-millimeters
-		    <td>1q = 1/40th of 1cm
+		    <td>1Q = 1/40th of 1cm
 		<tr><th><dfn id="in">in</dfn>
 		    <td>inches
 		    <td>1in = 2.54cm = 96px