Use stressRule instead of stressrule for consistency

docs/voices.md

@@ -25,6 +25,7 @@
   - [dictionary](#dictionary)
   - [dictrules](#dictrules)
   - [replace](#replace)
+  - [stressRule](#stressrule)
   - [stressLength](#stresslength)
   - [stressAdd](#stressadd)
   - [stressAmp](#stressamp)
@@ -372,6 +373,20 @@ e.g.
 The phoneme mnemonics can be defined for each language, but some are
 listed in [Phonemes](phonemes.md).
 
+### stressRule
+
+	stressRule <4 integer values>
+
+Four integer parameters. These correspond to:
+
+1. langopts->stress_rule (values in translate.h)
+2. langopts->stress_flags
+3. langopts->unstressed_wd1 (stress for $u word of 1 syllable)
+4. langopts->unstressed_wd2 (stress for $u word of >1 syllable) 
+
+If a value is not given, it defaults to zero. For example:
+"stressRule 2" is equal to "stressRule 2 0 0 0"
+
 ### stressLength
 
 	stressLength <8 integer values>