get rid of legacy RFC2119 style

The WebDriver specification is normative in its descriptions, and no
longer depends on RFC2119, and in particular its capitalised styling
of MUST, SHOULD, RECOMMENDED, MAY, et al.

This patch largely retains the words, but de-capitalises them.  In a
few cases it rewrites the sentence to make better sense in English.

Author: andreastt

index.html

@@ -418,7 +418,7 @@ <h3>Processing model</h3>
  and how it is established are out of scope.
 
 <p>After such a <a>connection</a> has been established,
- a <a>remote end</a> MUST run the following steps:</p>
+ a <a>remote end</a> must run the following steps:</p>
 
 <ol>
  <li><p><a>Read bytes</a> from the <a>connection</a> until a
@@ -1379,8 +1379,8 @@ <h2>Capabilities</h2>
  to describe the full feature set for a <a>session</a>.
 
 <p>The following <dfn>table of standard capabilities</dfn>
- enumerates the capabilities each implementation MUST support.
- An implementation MAY define additional <a>extension capabilities</a>.
+ enumerates the capabilities each implementation must support.
+ An implementation may define additional <a>extension capabilities</a>.
 
 <aside class="example">
 <p>As an example, Mozilla could elect to hide new features behind capabilities
@@ -2190,17 +2190,16 @@ <h3 id=new-session><dfn data-lt="new sessions|creating a new session">New Sessio
 If the creation fails, a <a>session not created</a> <a>error</a> is returned.
 
 <p>If the <a>remote end</a> is an <a>intermediary node</a>,
- it MAY use the result of the <a>capabilities processing</a> algorithm
+ it may use the result of the <a>capabilities processing</a> algorithm
  to route the <a>new session</a> request to the appropriate <a>endpoint node</a>.
- An <a>intermediary node</a> MAY also define <a>extension capabilities</a>
- to assist in this process, however, these specific capabilities MUST NOT be
- forwarded to the <a>endpoint node</a>.
+ An <a>intermediary node</a> is free to define <a>extension capabilities</a>
+ to assist in this process, however, these specific capabilities
+ must not be forwarded to the <a>endpoint node</a>.
 
-<p>If the <a>intermediary node</a> requires additional information
- unrelated to user agent features,
- it is RECOMMENDED that this information be passed as top-level parameters,
+<p>If the <a>intermediary node</a> requires additional information unrelated to user agent features,
+ it is recommended that this information be passed as top-level parameters,
  and not as part of the requested <a>capabilities</a>.
- An <a>intermediary node</a> MUST forward custom,
+ An <a>intermediary node</a> must forward custom,
  top-level parameters (i.e. non-<a>capabilities</a>) to subsequent <a>remote end</a> nodes.
 
 <aside class=example>
@@ -2218,9 +2217,8 @@ <h3 id=new-session><dfn data-lt="new sessions|creating a new session">New Sessio
 }</pre>
 
  <p>However, because an <a>intermediary node</a> cannot forward
- <a>extension capabilities</a> specific to that implementation to
- an <a>endpoint node</a>, the following is also permitted by this
- specification:
+ <a>extension capabilities</a> specific to that implementation to an <a>endpoint node</a>,
+ the following is also permitted by this specification:
 
  <pre>{
     "capabilities": {
@@ -2236,15 +2234,13 @@ <h3 id=new-session><dfn data-lt="new sessions|creating a new session">New Sessio
     }
 }</pre>
 
- <p>Once all <a data-lt="merging capabilities">capabilities are
-  merged</a> from this example, an <a>endpoint node</a> would receive
-  <a>New Session</a> capabilities identical to:
+ <p>Once all <a data-lt="merging capabilities">capabilities are merged</a> from this example,
+  an <a>endpoint node</a> would receive <a>New Session</a> capabilities identical to:
 
  <pre>[
     {"browserName": "chrome", "platformName": "linux"},
     {"browserName": "edge", "platformName": "linux"}
 ]</pre>
-
 </aside>
 
 <p>The <a>remote end steps</a> are: