Better document exact requirement specification (#5874)

* doc(*): better document exact requirements

* doc: move `Multiple requirements` under `Inequality requirements`

* doc: detail a bit more `add` possibilities

Author: mkniewallner

docs/cli.md

@@ -288,17 +288,28 @@ poetry will choose a suitable one based on the available package versions.
 poetry add requests pendulum
 ```
 
-You also can specify a constraint when adding a package, like so:
+You can also specify a constraint when adding a package:
 
 ```bash
+# Allow >=2.0.5, <3.0.0 versions
 poetry add pendulum@^2.0.5
+
+# Allow >=2.0.5, <2.1.0 versions
+poetry add pendulum@~2.0.5
+
+# Allow >=2.0.5 versions, without upper bound
 poetry add "pendulum>=2.0.5"
+
+# Allow only 2.0.5 version
+poetry add pendulum==2.0.5
 ```
 
 If you try to add a package that is already present, you will get an error.
 However, if you specify a constraint, like above, the dependency will be updated
-by using the specified constraint. If you want to get the latest version of an already
-present dependency you can use the special `latest` constraint:
+by using the specified constraint.
+
+If you want to get the latest version of an already
+present dependency, you can use the special `latest` constraint:
 
 ```bash
 poetry add pendulum@latest
@@ -319,8 +330,7 @@ or use ssh instead of https:
 ```bash
 poetry add git+ssh://[email protected]/sdispater/pendulum.git
 
-or alternatively:
-
+# or alternatively:
 poetry add git+ssh://[email protected]:sdispater/pendulum.git
 ```
 
@@ -331,8 +341,7 @@ you can specify it when using `add`:
 poetry add git+https://github.com/sdispater/pendulum.git#develop
 poetry add git+https://github.com/sdispater/pendulum.git#2.0.5
 
-or using SSH instead:
-
+# or using SSH instead:
 poetry add git+ssh://github.com/sdispater/pendulum.git#develop
 poetry add git+ssh://github.com/sdispater/pendulum.git#2.0.5
 ```

docs/dependency-specification.md

@@ -71,15 +71,18 @@ Here are some examples of inequality requirements:
 != 1.2.3
 ```
 
+#### Multiple requirements
+
+Multiple version requirements can also be separated with a comma, e.g. `>= 1.2, < 1.5`.
+
 ### Exact requirements
 
 You can specify the exact version of a package.
-This will tell Poetry to install this version and this version only.
-If other dependencies require a different version, the solver will ultimately fail and abort any install or update procedures.
 
-#### Multiple requirements
+`==1.2.3` is an example of an exact version specification.
 
-Multiple version requirements can also be separated with a comma, e.g. `>= 1.2, < 1.5`.
+This will tell Poetry to install this version and this version only.
+If other dependencies require a different version, the solver will ultimately fail and abort any install or update procedures.
 
 ## `git` dependencies