Fix the grammar in function examples of Beam3D

[JebronLames32]

References to other Issues or PRs

Brief description of what is fixed or changed

The example problems in most functions had a common grammatical error.
That has been changed in the respective functions.
The list of functions where change is made are:
plot_shear_force, plot_bending_moment, plot_slope,plot_deflection,
plot_loading_results, plot_shear_stress, max_shear_force, max_bending_moment,
max_deflection.

Other comments

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Release Notes

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#### References to other Issues or PRs
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#### Brief description of what is fixed or changed
The example problems in most functions had a common grammatical error.
That has been changed in the respective functions. 
The list of functions where change is made are:
plot_shear_force, plot_bending_moment, plot_slope,plot_deflection, 
plot_loading_results, plot_shear_stress, max_shear_force, max_bending_moment,
max_deflection.


#### Other comments
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#### Release Notes

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    reported the volt as being larger than the statvolt.

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[moorepants]

Remove the extra line.

[moorepants]

Thanks for the fix. Can you fully correct the sentences and remove the extra line?

Also, this does not need a release notes, use "NO ENTRY".

[JebronLames32]

Thanks for the fix. Can you fully correct the sentences and remove the extra line?

Also, this does not need a release notes, use "NO ENTRY".

Done. Please check now.

[moorepants]

You need to address this too:

This author is not included in the .mailmap file:
Abhinav R Cillanki <95158195+JebronLames32@users.noreply.github.com>

The .mailmap file needs to be updated because there are commits with
unrecognised author/email metadata.

        For instructions on updating the .mailmap file see:
https://docs.sympy.org/dev/contributing/new-contributors-guide/workflow-process.html#mailmap-instructions

The following authors will be added to the AUTHORS file at the time of
the next SymPy release.

[JebronLames32]

Made the change @moorepants

[1e9abhi1e10]

Made the change @moorepants

you need to run the following command python bin/mailmap_check.py after adding your name and email in the .mailmap file
read here for instructions.

[JebronLames32]

Made the change @moorepants

you need to run the following command python bin/mailmap_check.py after adding your name and email in the .mailmap file read here for instructions.

Thanks a lot

[github-actions]

Benchmark results from GitHub Actions

Lower numbers are good, higher numbers are bad. A ratio less than 1
means a speed up and greater than 1 means a slowdown. Green lines
beginning with + are slowdowns (the PR is slower then master or
master is slower than the previous release). Red lines beginning
with - are speedups.

Significantly changed benchmark results (PR vs master)

Significantly changed benchmark results (master vs previous release)

       before           after         ratio
     [271ca9f6]       [9e855bb8]
-         121±3ms         77.2±1ms     0.64  integrate.TimeIntegrationRisch02.time_doit(10)
-         121±4ms         73.8±3ms     0.61  integrate.TimeIntegrationRisch02.time_doit_risch(10)

Full benchmark results can be found as artifacts in GitHub Actions
(click on checks at the top of the PR).