use .bash as extension for bash completions

* bash-completions have code to use only `foo`, `foo.bash` and `_foo`
files for completion
* /usr is proper place for system-wide stuff rather than /etc

Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>

benches/06_rustup.rs

@@ -383,11 +383,11 @@ Unix and similar operating systems (such as GNU/Linux).
 
 BASH:
 
-Completion files are commonly stored in `/etc/bash_completion.d/`
+Completion files are commonly stored in `/usr/share/bash-completion/completions`
 
 Run the command:
 
-`rustup completions bash > /etc/bash_completion.d/rustup.bash-completion`
+`rustup completions bash > /usr/share/bash-completion/completions/rustup.bash`
 
 This installs the completion script. You may have to log out and log
 back in to your shell session for the changes to take affect.

src/app/mod.rs

@@ -1375,9 +1375,9 @@ impl<'a, 'b> App<'a, 'b> {
     ///                         outdir);      // Then say where write the completions to
     /// }
     /// ```
-    /// Now, once we compile there will be a `{bin_name}.bash-completion` file in the directory.
+    /// Now, once we compile there will be a `{bin_name}.bash` file in the directory.
     /// Assuming we compiled with debug mode, it would be somewhere similar to
-    /// `<project>/target/debug/build/myapp-<hash>/out/myapp.bash-completion`.
+    /// `<project>/target/debug/build/myapp-<hash>/out/myapp.bash`.
     ///
     /// Fish shell completions will use the file format `{bin_name}.fish`
     pub fn gen_completions<T: Into<OsString>, S: Into<String>>(&mut self,
@@ -1419,7 +1419,7 @@ impl<'a, 'b> App<'a, 'b> {
     /// Usage:
     ///
     /// ```shell
-    /// $ myapp generate-bash-completions > /etc/bash_completion.d/myapp
+    /// $ myapp generate-bash-completions > /usr/share/bash-completion/completions/myapp.bash
     /// ```
     pub fn gen_completions_to<W: Write, S: Into<String>>(&mut self,
                                                          bin_name: S,

src/app/parser.rs

@@ -114,7 +114,7 @@ impl<'a, 'b> Parser<'a, 'b>
         let out_dir = PathBuf::from(od);
         let name = &*self.meta.bin_name.as_ref().unwrap().clone();
         let file_name = match for_shell {
-            Shell::Bash => format!("{}.bash-completion", name),
+            Shell::Bash => format!("{}.bash", name),
             Shell::Fish => format!("{}.fish", name),
             Shell::Zsh => format!("_{}", name),
             Shell::PowerShell => format!("_{}.ps1", name),

src/completions/shell.rs

@@ -7,7 +7,7 @@ use std::fmt;
 #[cfg_attr(feature = "lints", allow(enum_variant_names))]
 #[derive(Debug, Copy, Clone)]
 pub enum Shell {
-    /// Generates a .bash-completion completion file for the Bourne Again SHell (BASH)
+    /// Generates a .bash completion file for the Bourne Again SHell (BASH)
     Bash,
     /// Generates a .fish completion file for the Friendly Interactive SHell (fish)
     Fish,