test: Use POSIX-compliant example for equals comparison (#11728)

* [: use posix-compliant example for equals comparison

the previous example worked fine for bash, but some
other shells (zsh, in my case) will not work when
using "==" for comparison. the posix spec only requires
"=", so I think it makes a little more sense to use
that in the example.

* test: use posix-compliant example for equals comparison

the previous example worked fine for bash, but some
other shells (zsh, in my case) will not work when
using "==" for comparison. the posix spec only requires
"=", so I think it makes a little more sense to use
that in the example.

pages/common/[.md

@@ -6,7 +6,7 @@
 
 - Test if a given variable is equal/not equal to the specified string:
 
-`[ "${{variable}}" {{==|!=}} "{{string}}" ]`
+`[ "${{variable}}" {{=|!=}} "{{string}}" ]`
 
 - Test if a given variable is [eq]ual/[n]ot [e]qual/[g]reater [t]han/[l]ess [t]han/[g]reater than or [e]qual/[l]ess than or [e]qual to the specified number:
 

pages/common/test.md

@@ -6,7 +6,7 @@
 
 - Test if a given variable is equal to a given string:
 
-`test "{{$MY_VAR}}" == "{{/bin/zsh}}"`
+`test "{{$MY_VAR}}" = "{{/bin/zsh}}"`
 
 - Test if a given variable is empty: