apply editorial suggestions from @MikeBishop as well as reorganizing …

…the paragraph.

draft-ietf-quic-http.md

@@ -613,12 +613,11 @@ tree could be discarded safely. Clients could potentially reference closed
 streams long after the server had discarded state, leading to disparate views of
 the prioritization the client had attempted to express.
 
-In HTTP/3, placeholders are given their own number space that spans between zero
-and 2^62-1.  By using the `SETTINGS_NUM_PLACEHOLDERS` setting, the server
-advertises the range of placeholder IDs it is committing to maintain state,
-which is between zero and one less than the value of this setting.  Clients can
-use the placeholders within this range with the confidence that the server will
-not have discarded the state.
+In HTTP/3, by using the `SETTINGS_NUM_PLACEHOLDERS` setting, the server
+advertises the number of placeholders it is committing to maintain state.
+Placeholders are given their own number space that spans between zero and
+2^62-1.  Clients can use the placeholders with an ID less than the value of this
+setting with the confidence that the server will not have discarded the state.
 
 Clients MUST NOT send the `SETTINGS_NUM_PLACEHOLDERS` setting; receipt of this
 setting by a server MUST be treated as a connection error of type