gem: add examples for searching and uninstalling (#3172)

pages/common/gem.md

@@ -3,22 +3,34 @@
 > Interact with the package manager for the Ruby programming language.
 > More information: <https://rubygems.org>.
 
+- Search for remote gem(s):
+
+`gem search {{regexp}}`
+
+- Search for remote gem(s) and show all available versions:
+
+`gem search {{regexp}} --all`
+
 - Install latest version of a gem:
 
 `gem install {{gemname}}`
 
 - Install specific version of a gem:
 
-`gem install {{gemname}} -v {{1.0.0}}`
+`gem install {{gemname}} --version {{1.0.0}}`
 
 - Update a gem:
 
 `gem update {{gemname}}`
 
-- List all gems:
+- List all local gems:
 
 `gem list`
 
 - Uninstall a gem:
 
 `gem uninstall {{gemname}}`
+
+- Uninstall specific version of a gem:
+
+`gem uninstall {{gemname}} --version {{1.0.0}}`