Add documentation for changelog flags in bundle gem

The --changelog and --no-changelog flags are missing from docs, this adds them in a way that matches other flags

Author: addersuk

bundler/lib/bundler/man/bundle-gem.1

@@ -28,6 +28,10 @@ The generated project skeleton can be customized with OPTIONS, as explained belo
 .IP "\(bu" 4
 \fB\-\-no\-coc\fR: Do not create a \fBCODE_OF_CONDUCT\.md\fR (overrides \fB\-\-coc\fR specified in the global config)\.
 .IP "\(bu" 4
+\fB\-\-changelog\fR Add a \fBCHANGELOG\.md\fR file to the root of the generated project\. If this option is unspecified, an interactive prompt will be displayed and the answer will be saved in Bundler's global config for future \fBbundle gem\fR use\.
+.IP "\(bu" 4
+\fB\-\-no\-changelog\fR: Do not create a \fBCHANGELOG\.md\fR (overrides \fB\-\-changelog\fR specified in the global config)\.
+.IP "\(bu" 4
 \fB\-\-ext=c\fR, \fB\-\-ext=rust\fR Add boilerplate for C or Rust (currently magnus \fIhttps://docs\.rs/magnus\fR based) extension code to the generated project\. This behavior is disabled by default\.
 .IP "\(bu" 4
 \fB\-\-no\-ext\fR: Do not add extension code (overrides \fB\-\-ext\fR specified in the global config)\.

bundler/lib/bundler/man/bundle-gem.1.ronn

@@ -41,6 +41,15 @@ configuration file using the following names:
   Do not create a `CODE_OF_CONDUCT.md` (overrides `--coc` specified in the
   global config).
 
+* `--changelog`
+  Add a `CHANGELOG.md` file to the root of the generated project. If
+  this option is unspecified, an interactive prompt will be displayed and the
+  answer will be saved in Bundler's global config for future `bundle gem` use.
+
+* `--no-changelog`:
+  Do not create a `CHANGELOG.md` (overrides `--changelog` specified in the
+  global config).
+
 * `--ext=c`, `--ext=rust`
   Add boilerplate for C or Rust (currently [magnus](https://docs.rs/magnus) based) extension code to the generated project. This behavior
   is disabled by default.